Controlled Architecture Polymerization with Photoinitiator Groups in Backbone

ABSTRACT

Acrylic copolymers that include the controlled placement of particular functional groups within the polymer structure are provided. The copolymers comprise a first reactive segment of including a functional group selected from the group consisting of a UV active functional group, a reactive functional group, a non-reactive functional group, and combinations thereof and a second segment including a functional group selected from the group consisting of a reactive functional group, a non-reactive functional group, and combinations thereof. The acrylic copolymers are manufactured via a controlled radical polymerization process. The copolymers are useful in the manufacture of adhesives and elastomers.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of U.S. Provisional PatentApplication No. 62/412,326 filed Oct. 25, 2016, which is incorporatedherein by reference in its entirety.

BACKGROUND

The subject matter relates to acrylic polymers, and in particular, toacrylic copolymers that include controlled placement of reactivefunctional groups within the polymer structure. The copolymers areuseful in the manufacture of adhesives and elastomers.

(Meth)acrylic (co)polymers have been studied and used industrially formore than 50 years. Due to a wide range of monomers, (meth)acrylic(co)polymers display a significant array of viscoelastic properties thatlend themselves well to applications in adhesives and elastomers. Whencompared to other copolymers that are used for similar purposes as(meth)acrylics, several significant advantages of (meth)acrylics becomeapparent. For example, relative to natural rubber and styrene blockcopolymers (meth)acrylic copolymers have superior optical clarity, UVstability, and temperature and oxidative resistance. State of the art(meth)acrylic copolymers meet many performance characteristics by virtueof their high molecular weight and crosslinking reactions. Because ofthe wide array of copolymerizable monomers, (meth)acrylic polymers havetailorable polarity and the ability to undergo a variety of crosslinkingreactions. Typically, high performance (meth)acrylic copolymers areprocessed with large amounts of organic solvents.

Increasingly, there are significant economic and regulatory pressuresfor producers of solvent acrylic polymers to reduce the use of organicsolvents in their processes. In particular, it is common for solventacrylic polymers in adhesive applications to be coated from solutionsaveraging only 30-40% polymer. The solvent has to be evaporated and theneither collected or incinerated, all of which are energy intensive andcostly operations. Additionally, removal of solvent from thick adhesivefilms may produce defects in the dry adhesive film.

Control of polymer architecture is often the subject of intensiveresearch with the goal of improving performance for ever increasinglychallenging applications. Architectures that acrylic polymers are knownto possess include block copolymers, telechelic polymers, and randompolymers of controlled molecular weight. Even though advances incontrolling architecture have occurred with many benefits, each of theseparticular architectural types has disadvantages. For example, blockcopolymers have high melt viscosities which require high processingtemperatures, making it difficult to control reactivity of functionalgroups. The production of telechelic polymers often involves multiplesteps. Telechelics involve the placement of a reactive functional groupexclusively on the end terminus of a polymer and not elsewhere in thepolymer backbone. Functional groups placed at the end termini ofpolymers serve solely to increase the linear molecular weight in amanner in which free polymer chain ends are eliminated. As a result,telechelic polymers can yield high strength materials but do not providethe viscoelastic properties critical to adhesives and some elastomerapplications. Random polymers of controlled molecular weight requirehigh amounts of crosslinking to attain network formation.

In the past 15-20 years a variety of controlled radical polymerizationtechniques have been developed to afford good architectural control of(meth)acrylic monomers. These techniques typically are tolerant to awide variety of monomers and functional groups as opposed to previoustechniques like anionic or group transfer polymerization. A substantialamount of fundamental research has been performed to understand thesetypes of polymerization and a thorough review has been edited byMatyjewski. Reversible addition fragmentation chain transfer (RAFT)polymerization is one such technique that has been shown to workexceedingly well with a wide variety of (meth)acrylic monomers yieldingexcellent control of molecular weight and polydispersity. The RAFTmechanism for controlled polymerization is well understood and reportedextensively. While some examples of controlled architecture acrylic PSAshave been reported, very little work has been done to explore theinfluence of reactive functional group placement.

SUMMARY

The present subject matter addresses problems associated with previouslyknown architectured polymers by placement of crosslinkable monomers intosegments of the polymer of controlled molecular weight and position. Theoverall molecular weight is low which yields desirable low viscosity,high solids solutions and melts. In conjunction with goodprocessability, high performance elastomers and adhesives are obtainedupon crosslinking. In particular, the crosslinkable monomers are placedin specific segments of the polymer backbone so that the crosslinkdensity is controlled for optimal performance. The compositions of thepresent subject matter contain no undesired heterogeneity prior tocrosslinking. A further benefit is that in all embodiments of thesubject matter, the polymer chain ends are preserved to yield desiredvisco-elastic and surface properties. To control the placement ofcrosslinkable monomers, it is preferred to employ a controlled freeradical polymerization technique. In contrast with standard free radicalprocesses it is now possible to control the placement of crosslinkablemonomers.

The present subject matter provides an acrylic block copolymercomposition comprising at least one of an (A-B) diblock copolymer,(A-B-A) triblock copolymer, an -(A-B)_(n)-multiblock copolymer, andcombinations thereof, whereby A is a first reactive segment and B is asecond reactive segment. The present subject matter also provides apressure sensitive adhesive derived from an acrylic block copolymercomposition comprising at least one of an (A-B) diblock copolymer,(A-B-A) triblock copolymer, an -(A-B)_(n)-multiblock copolymer, andcombinations thereof, whereby A is a first reactive segment and B is asecond reactive segment. The present subject matter further provides amethod of preparing an acrylic block copolymer (and/or a method ofpreparing a pressure sensitive adhesive derived from an acrylic blockcopolymer composition) comprising at least one of an (A-B) diblockcopolymer, (A-B-A) triblock copolymer, an -(A-B)_(n)-multiblockcopolymer, and combinations thereof, whereby A is a first reactivesegment and B is a second reactive segment. The present subject matteralso provides use of an acrylic block copolymer (and/or a pressuresensitive adhesive derived from an acrylic block copolymer) compositioncomprising at least one of an (A-B) diblock copolymer, (A-B-A) triblockcopolymer, an -(A-B)_(n)-multiblock copolymer, and combinations thereof,whereby A is a first reactive segment and B is a second reactivesegment.

In one aspect, the present subject matter provides an acrylic polymercomprising at least one acrylic block copolymer including (i) a firstreactive segment of controlled molecular weight and position thatincludes at least one monomer having a functional group selected fromthe group consisting of a UV active functional group, a reactivefunctional group, a non-reactive functional group, and combinationsthereof, and (ii) a second segment of controlled molecular weight andposition that includes at least one monomer having a functional groupselected from the group consisting of a reactive functional group, anon-reactive functional group, and combinations thereof. The reactivefunctionalities in the first reactive segment and the second segment maybe the same or different from one another. The non-reactivefunctionalities in the first reactive segment and the second segment maybe the same or different from one another. In some embodiments, thefirst reactive segment includes at least one monomer having a UV activefunctional group, at least one monomer having a reactive functionalgroup, and at least one monomer having a non-reactive functional group.The second segment includes at least one monomer having a reactivefunctional group and at least one monomer having a non-reactivefunctional group. In other embodiments, the first reactive segmentincludes at least one monomer having a UV active functional group and atleast one monomer having a non-reactive functional group. The secondsegment includes at least one monomer having a non-reactive functionalgroup or at least one monomer having only a non-reactive functionalgroup. The second segment is non-reactive with the UV active functionalgroup or the reactive functional group. The at least one monomer havinga non-reactive functional group is non-reactive with the UV activefunctional group and/or the reactive functional group. The firstreactive segment and the second segment may be positioned adjacent tothe polymer chain ends. The reactive functional groups and/or thenon-reactive functional groups may be spaced apart along the length ofthe polymer chain. That is, the reactive functional groups and/or thenon-reactive functional groups are spaced apart along the length of thefirst reactive segment and/or along the length of the second segment.The reactive functional groups and/or the non-reactive functional groupsmay be randomly spaced apart along the length of the polymer chain. Thatis, the reactive functional groups and/or the non-reactive functionalgroups may be randomly spaced apart along the length of the firstreactive segment and/or along the length of the second segment. The atleast one monomer having a UV active functional group is about 10% orless, or about 5% or less, or about 4% or less, or about 3% or less byweight of the total polymer weight. The first reactive segment comprises40% or less, 30% or less, 20% or less, 10% or less, 5% or less, or 3% orless of the total polymer molecular weight. The first reactivesegment(s) include about 40% to about 99%, or about 45% to about 99%, orabout 0% to about 99%, or about 55% to about 99%, or about 60% to about99%, or about 65% to about 99%, or about 70% to about 99%, or about 75%to about 99%, or about 80% to about 99%, or about 85% to about 99%, orabout 90% to about 99%, or about 95% to about 99% by weight of one ormore non-reactive monomers. The functional groups of the first reactivesegment and the second segment are capable of undergoing crosslinkingreactions. The first reactive segment and the second segment aremolecularly miscible before cure as expressed by their properties in thebulk state that are indicative of a single phase behavior or a singlephase polymer. That is, the acrylic polymer is a single phase polymerprior to crosslinking. The acrylic polymer is a homogeneous polymerprior to crosslinking. The acrylic polymer is a homogeneous polymer atroom temperature.

In some embodiments, the acrylic polymer is a single phase polymer atroom temperature.

In another embodiment, the acrylic polymer is a single phase liquidpolymer prior to crosslinking.

In yet another embodiment, the acrylic polymer is a single phase liquidpolymer at room temperature.

In still another embodiment, the acrylic polymer is a homogeneouspolymer prior to crosslinking.

In yet another embodiment, the acrylic polymer is a homogeneous polymerat room temperature.

In certain embodiments, the acrylic polymer is a homogeneous liquidpolymer prior to crosslinking.

In some embodiments, the acrylic polymer is a homogeneous liquid polymerat room temperature.

In another embodiment, the acrylic polymer is a liquid polymer prior tocrosslinking.

In yet another embodiment, the acrylic polymer is a liquid polymer atroom temperature.

In still another embodiment, the acrylic polymer exhibits noheterogeneity prior to crosslinking.

In yet another embodiment, the acrylic polymer exhibits no heterogeneityat room temperature.

In another aspect, the present subject matter provides an acrylicpolymer comprising at least one acrylic block copolymer including twofirst reactive segments A of controlled molecular weight and positionand one second segment B of controlled molecular weight and position,wherein the first reactive segments A is positioned on either side of amiddle second segment B on the polymer chain to define an ABA structure.The first reactive segments A includes at least one monomer having afunctional group selected from the group consisting of a UV activefunctional group, a reactive functional group, a non-reactive functionalgroup, and combinations thereof. The second segment B includes at leastone monomer having a functional group selected from the group consistingof a reactive functional group, a non-reactive functional group, andcombinations thereof. The reactive functionalities in the first reactivesegment A and the second segment B may be the same or different from oneanother. The non-reactive functionalities in the first reactive segmentA and the second segment B may be the same or different from oneanother. In some embodiments, the first reactive segment includes atleast one monomer having a UV active functional group, at least onemonomer having a reactive functional group, and at least one monomerhaving a non-reactive functional group. The second segment includes atleast one monomer having a reactive functional group and at least onemonomer having a non-reactive functional group. In other embodiments,the first reactive segment includes at least one monomer having a UVactive functional group and at least one monomer having a non-reactivefunctional group. The second segment includes at least one monomerhaving a having a non-reactive functional group or at least one monomerhaving only a non-reactive functional group. The second segment isnon-reactive with the UV active functional group or the reactivefunctional group. The at least one monomer having a non-reactivefunctional group is non-reactive with the UV active functional groupand/or the reactive functional group. The first reactive segments arepositioned adjacent to the polymer chain ends. The reactive functionalgroups and/or the non-reactive functional groups may be spaced apartalong the length of the polymer chain. That is, the reactive functionalgroups and/or the non-reactive functional groups may be spaced apartalong the length of the first reactive segment and/or along the lengthof the second segment. The reactive functional groups and/or thenon-reactive functional groups may be randomly spaced apart along thelength of the polymer chain. That is, the reactive functional groupsand/or the non-reactive functional groups may be randomly spaced apartalong the length of the first reactive segment and/or along the lengthof the second segment. The at least one monomer having a UV activefunctional group is about 10% or less, or about 5% or less, or about 4%or less, or about 3% or less by weight of the total polymer weight. Thefirst reactive segment comprises 40% or less, 30% or less, 20% or less,10% or less, 5% or less, or 3% or less of the total polymer molecularweight. The first reactive segment(s) include about 40% to about 99%, orabout 45% to about 99%, or about 50% to about 99%, or about 55% go about99%, or about 60% to about 99%, or about 65% go about 99%, or about 70%to about 99%, or about 75% go about 99%, or about 80% to about 99%, orabout 85% to about 99%, or about 90% to about 99%, or about 95% to about99% by weight of one or more non-reactive monomers. The functionalgroups of the first reactive segment and the second segment are capableof undergoing crosslinking reactions. The first reactive segments A andthe second segment B are molecularly miscible before cure as expressedby their properties in the bulk state that are indicative of a singlephase behavior or a single phase polymer. That is, the acrylic polymeris a single phase polymer prior to crosslinking. The acrylic polymer isa homogeneous polymer prior to crosslinking. The acrylic polymer is ahomogeneous polymer at room temperature.

In some embodiments, the acrylic polymer is a single phase polymer atroom temperature. In another embodiment, the acrylic polymer is a singlephase liquid polymer prior to crosslinking. In yet another embodiment,the acrylic polymer is a single phase liquid polymer at roomtemperature. In certain embodiments, the acrylic polymer is ahomogeneous liquid polymer prior to crosslinking. In some embodiments,the acrylic polymer is a homogeneous liquid polymer at room temperature.In another embodiment, the acrylic polymer is a liquid polymer prior tocrosslinking. In yet another embodiment, the acrylic polymer is a liquidpolymer at room temperature. In still another embodiment, the acrylicpolymer exhibits no heterogeneity prior to crosslinking. In yet anotherembodiment, the acrylic polymer exhibits no heterogeneity at roomtemperature.

In another aspect, the present subject matter provides an acrylicpolymer comprising two second segments B and one first reactive segmentA, wherein the segments B may be positioned on either side of the middlesegment A on the polymer chain to define a BAB structure.

In another aspect, the present subject matter provides a pressuresensitive adhesive composition comprising at least one acrylic blockcopolymer including (i) a first reactive segment of controlled molecularweight and position that includes at least one monomer having afunctional group selected from the group consisting of a UV activefunctional group, a reactive functional group, a non-reactive functionalgroup, and combinations thereof, and (ii) a second segment of controlledmolecular weight and position that includes at least one monomer havinga functional group selected from the group consisting of a reactivefunctional group, a non-reactive functional group, and combinationsthereof. The reactive functionalities in the first reactive segment andthe second segment may be the same or different from one another. Thenon-reactive functionalities in the first reactive segment and thesecond segment may be the same or different from one another. In someembodiments, the first reactive segment includes at least one monomerhaving a UV active functional group, at least one monomer having areactive functional group, and at least one monomer having anon-reactive functional group. The second segment includes at least onemonomer having a reactive functional group and at least one monomerhaving a non-reactive functional group. In other embodiments, the firstreactive segment includes at least one monomer having a UV activefunctional group and at least one monomer having a non-reactivefunctional group. The second segment includes at least one monomerhaving a having a non-reactive functional group or at least one monomerhaving only a non-reactive functional group. The second segment isnon-reactive with the UV active functional group or the reactivefunctional group. The at least one monomer having a non-reactivefunctional group is non-reactive with the UV active functional groupand/or the reactive functional group. The first reactive segment and thesecond segment may be positioned adjacent to the polymer chain ends. Thereactive functional groups and/or the non-reactive functional groups maybe spaced apart along the length of the polymer chain. That is, thereactive functional groups and/or the non-reactive functional groups maybe spaced apart along the length of the first reactive segment and/oralong the length of the second segment. The reactive functional groupsand/or the non-reactive functional groups may be randomly spaced apartalong the length of the polymer chain. That is, the reactive functionalgroups and/or the non-reactive functional groups may be randomly spacedapart along the length of the first reactive segment and/or along thelength of the second segment. The at least one monomer having a UVactive functional group is about 10% or less, or about 5% or less, orabout 4% or less, or about 3% or less by weight of the total polymerweight. The first reactive segment comprises 40% or less, 30% or less,20% or less, 10% or less, 5% or less, or 3% or less of the total polymermolecular weight. The first reactive segment(s) include about 40% toabout 99%, or about 45%© to about 99%, or about 50% to about 99%, orabout 55% to about 99%, or about 60% to about 99%, or about 65% to about99%, or about 70% to about 99%, or about 75% to about 99%, or about 80%to about 99%, or about 85% to about 99%, or about 90% to about 99%, orabout 95% to about 99% by weight of one or more non-reactive monomers.The functional groups of the first reactive segment and the secondsegment are capable of undergoing crosslinking reactions. The firstreactive segment and the second segment are molecularly miscible beforecure as expressed by their properties in the bulk state that areindicative of a single phase behavior or a single phase polymer. Thatis, the acrylic polymer is a single phase polymer prior to crosslinking.The acrylic polymer is a homogeneous polymer prior to crosslinking. Theacrylic polymer is a homogeneous polymer at room temperature.

In some embodiments, the acrylic polymer is a single phase polymer atroom temperature. In another embodiment, the acrylic polymer is a singlephase liquid polymer prior to crosslinking. In yet another embodiment,the acrylic polymer is a single phase liquid polymer at roomtemperature. In certain embodiments, the acrylic polymer is ahomogeneous liquid polymer prior to crosslinking. In some embodiments,the acrylic polymer is a homogeneous liquid polymer at room temperature.In another embodiment, the acrylic polymer is a liquid polymer prior tocrosslinking. In yet another embodiment, the acrylic polymer is a liquidpolymer at room temperature. In still another embodiment, the acrylicpolymer exhibits no heterogeneity prior to crosslinking. In yet anotherembodiment, the acrylic polymer exhibits no heterogeneity at roomtemperature.

A widely acceptable quantitative description of a pressure sensitiveadhesive (PSA) is given by the Dahlquist criterion, which indicates thatmaterials having an elastic modulus (G′) of less than 3×10⁶ dynes/cm²(i.e., 3×10⁵ Pa) on a 1-s time scale at the test temperature have PSAproperties while materials having a G′ in excess of this value do not.Empirically, it was found that materials that exhibit pressuresensitivity are those that are sufficiently soft, exhibiting an elasticmodulus of less than 3×10⁵ Pa (3×10⁶ dyn/cm²) on a 1-s time scale at thetest temperature. This somewhat surprising but well accepted empiricalcriterion was first established by Dahlquist and is commonly referred asthe “Dahlquist criterion”. Exemplary PSAs of the instant applicationshown in FIG. 12 display plateau elastic/storage modulus (G′) of lessthan 3×10⁶ dynes/cm² (i.e., 3×10⁵ Pa) at room temperature indicatingthat the adhesives contemplated in the instant application are PSAs.

In still another aspect, the present subject matter provides a method ofpreparing a pressure sensitive adhesive composition comprisingpolymerizing using a controlled radical polymerization process at leastone monomer having a functional group selected from the group consistingof a UV active functional group, a reactive functional group, anon-reactive functional group, and combinations thereof to thereby forma first reactive segment of controlled molecular weight and position.The method also comprises polymerizing using a controlled radicalpolymerization process at least one monomer having a functional groupselected from the group consisting of a reactive functional group, anon-reactive functional group, and combinations thereof to thereby forma second segment of controlled molecular weight and position. Thereactive functionalities in the first reactive segment and the secondsegment may be the same or different from one another. The non-reactivefunctionalities in the first reactive segment and the second segment maybe the same or different from one another. In some embodiments, thefirst reactive segment includes at least one monomer having a UV activefunctional group, at least one monomer having a reactive functionalgroup, and at least one monomer having a non-reactive functional group.The second segment includes at least one monomer having a reactivefunctional group and at least one monomer having a non-reactivefunctional group. In other embodiments, the first reactive segmentincludes at least one monomer having a UV active functional group and atleast one monomer having a non-reactive functional group. The secondsegment includes at least one monomer having a having a non-reactivefunctional group or at least one monomer having only a non-reactivefunctional group. The second segment is non-reactive with the UV activefunctional group or the reactive functional group. The at least onemonomer having a non-reactive functional group is non-reactive with theUV active functional group and/or the reactive functional group. Thefirst reactive segment and the second segment may be positioned adjacentto the polymer chain ends. The reactive functional groups and/or thenon-reactive functional groups may be spaced apart along the length ofthe polymer chain. That is, the reactive functional groups and/or thenon-reactive functional groups may be spaced apart along the length ofthe first reactive segment and/or along the length of the secondsegment. The reactive functional groups and/or the non-reactivefunctional groups may be randomly spaced apart along the length of thepolymer chain. That is, the reactive functional groups and/or thenon-reactive functional groups may be randomly spaced apart along thelength of the first reactive segment and/or along the length of thesecond segment. The at least one monomer having a UV active functionalgroup is about 10% or less, or about 5% or less, or about 4% or less, orabout 3% or less by weight of the total polymer weight. The firstreactive segment comprises 40% or less, 30% or less, 20% or less, 10% orless, 5% or less, or 3% or less of the total polymer molecular weight.The first reactive segment(s) include about 40%© to about 99%, or about45% to about 99%, or about 50′%© to about 99%, or about 55′%© to about99%, or about 60′%© to about 99%, or about 65% to about 99%, or about70% to about 99%, or about 75% to about 99%, or about 80% to about 99%,or about 85% to about 99%, or about 90% to about 99%, or about 95% toabout 99% by weight of one or more non-reactive monomers. The functionalgroups of the first reactive segment and the second segment are capableof undergoing crosslinking reactions. At least one of the first reactivesegment and the second segment includes an acrylate group. The methodalso comprises forming an acrylic polymer from the first reactivesegment and the second segment. The method additionally comprisescrosslinking the acrylic polymer by mixing the acrylic polymer with anamount of a crosslinking agent. The first reactive segment and thesecond segment are molecularly miscible before cure as expressed bytheir properties in the bulk state that are indicative of a single phasebehavior or a single phase polymer. That is, the acrylic polymer is asingle phase polymer prior to crosslinking. The acrylic polymer is ahomogeneous polymer prior to crosslinking. The acrylic polymer is ahomogeneous polymer at room temperature.

In some embodiments, the acrylic polymer is a single phase polymer atroom temperature. In another embodiment, the acrylic polymer is a singlephase liquid polymer prior to crosslinking. In yet another embodiment,the acrylic polymer is a single phase liquid polymer at roomtemperature. In certain embodiments, the acrylic polymer is ahomogeneous liquid polymer prior to crosslinking. In some embodiments,the acrylic polymer is a homogeneous liquid polymer at room temperature.In another embodiment, the acrylic polymer is a liquid polymer prior tocrosslinking. In yet another embodiment, the acrylic polymer is a liquidpolymer at room temperature. In still another embodiment, the acrylicpolymer exhibits no heterogeneity prior to crosslinking. In yet anotherembodiment, the acrylic polymer exhibits no heterogeneity at roomtemperature.

In yet another aspect, the present subject matter provides an adhesivearticle comprising a substrate and an adhesive disposed on thesubstrate. The adhesive includes at least one acrylic block copolymerhaving (i) a first reactive segment of controlled molecular weight andposition that includes at least one monomer having a functional groupselected from the group consisting of a UV active functional group, areactive functional group, a non-reactive functional group, andcombinations thereof, and (ii) a second segment of controlled molecularweight and position that includes at least one monomer having afunctional group selected from the group consisting of a reactivefunctional group, a non-reactive functional group, and combinationsthereof. The reactive functionalities in the first reactive segment andthe second segment may be the same or different from one another. Thenon-reactive functionalities in the first reactive segment and thesecond segment may be the same or different from one another. In someembodiments, the first reactive segment includes at least one monomerhaving a UV active functional group, at least one monomer having areactive functional group, and at least one monomer having anon-reactive functional group. The second segment includes at least onemonomer having a reactive functional group and at least one monomerhaving a non-reactive functional group. In other embodiments, the firstreactive segment includes at least one monomer having a UV activefunctional group and at least one monomer having a non-reactivefunctional group. The second segment includes at least one monomerhaving a having a non-reactive functional group or at least one monomerhaving only a non-reactive functional group. The second segment isnon-reactive with the UV active functional group or the reactivefunctional group. The at least one monomer having a non-reactivefunctional group is non-reactive with the UV active functional groupand/or the reactive functional group. The first reactive segment and thesecond segment may be positioned adjacent to the polymer chain ends. Thereactive functional groups and/or the non-reactive functional groups arespaced apart along the length of the polymer chain. That is, thereactive functional groups and/or the non-reactive functional groups maybe spaced apart along the length of the first reactive segment and/oralong the length of the second segment. The reactive functional groupsand/or the non-reactive functional groups may be randomly spaced apartalong the length of the polymer chain. That is, the reactive functionalgroups and/or the non-reactive functional groups may be randomly spacedapart along the length of the first reactive segment and/or along thelength of the second segment. The at least one monomer having a UVactive functional group is about 10% or less, or about 5% or less, orabout 4% or less, or about 3% or less by weight of the total polymerweight. The first reactive segment comprises 40% or less, 30% or less,20% or less, 10% or less, 5% or less, or 3% or less of the total polymermolecular weight. The first reactive segment(s) include about 40% toabout 99%, or about 45% to about 99%, or about 50% go about 99%, orabout 55% to about 99%, or about 60% to about 99%, or about 65% go about99%, or about 70% to about 99%, or about 75% to about 99%, or about 80%to about 99%, or about 85% to about 99%, or about 90% to about 99%, orabout 95% to about 99% by weight of one or more non-reactive monomers.The functional groups of the first reactive segment and the secondsegment are capable of undergoing crosslinking reactions. The firstreactive segment and the second segment are molecularly miscible beforecure as expressed by their properties in the bulk state that areindicative of a single phase behavior or a single phase polymer. Thatis, the acrylic polymer is a single phase polymer prior to crosslinking.The acrylic polymer is a homogeneous polymer prior to crosslinking. Theacrylic polymer is a homogeneous polymer at room temperature.

In some embodiments, the acrylic polymer is a single phase polymer atroom temperature. In another embodiment, the acrylic polymer is a singlephase liquid polymer prior to crosslinking. In yet another embodiment,the acrylic polymer is a single phase liquid polymer at roomtemperature. In still another embodiment, the acrylic polymer is ahomogeneous polymer prior to crosslinking. In yet another embodiment,the acrylic polymer is a homogeneous polymer at room temperature. Incertain embodiments, the acrylic polymer is a homogeneous liquid polymerprior to crosslinking. In some embodiments, the acrylic polymer is ahomogeneous liquid polymer at room temperature. In another embodiment,the acrylic polymer is a liquid polymer prior to crosslinking. In yetanother embodiment, the acrylic polymer is a liquid polymer at roomtemperature. In still another embodiment, the acrylic polymer exhibitsno heterogeneity prior to crosslinking. In yet another embodiment, theacrylic polymer exhibits no heterogeneity at room temperature.

As used herein, room temperature is from about 15° to about 25° C. Asused herein, the term “liquid at room temperature” means a polymer thatundergoes a degree of cold flow at room temperature. Cold flow is thedistortion, deformation or dimensional change that takes place inmaterials under continuous load at temperatures within the workingrange. Cold flow is not due to heat softening.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a process schematic diagram showing a representative processand system for producing an adhesive in accordance with the presentsubject matter.

FIG. 2 is a schematic illustration of a tape article including anadhesive in accordance with the present subject matter.

FIG. 3 is a schematic cross sectional view of another tape article inaccordance with the present subject matter.

FIG. 4 is a schematic cross sectional view of another tape article inaccordance with the present subject matter.

FIG. 5 is a schematic cross sectional view of another tape article inaccordance with the present subject matter.

FIG. 6 is a schematic cross sectional view of another tape article inaccordance with the present subject matter.

FIG. 7 is a schematic cross sectional view of a sealing or closureassembly including a region of an adhesive in accordance with thepresent subject matter.

FIG. 8 is a graph of adhesion versus dosage for samples described inexamples herein.

FIG. 9 is a graph of percentage of insolubles versus dosage for samplesdescribed in examples herein.

FIG. 10 is a graph of melt flow viscosity versus temperature for samplesof Example 1 herein.

FIG. 11 is a graph of melt flow viscosity versus temperature for samplesof Example 6 herein.

FIG. 12 is a plot of elastic/storage modulus as a function oftemperature for samples of Examples 1-3, 5, and 6 described herein.

FIG. 13 is a plot of tan (delta) versus temperature for samples ofExamples 1-3, 5, and 6 described herein.

DETAILED DESCRIPTION

As used herein, terms such as “typically” are not intended to limit thescope of the claimed invention or to imply that certain features arecritical, essential, or even important to the structure or function ofthe claimed invention. Rather, these terms are merely intended tohighlight alternative or additional features that may or may not beutilized in a particular embodiment of the present invention.

As used herein, the terms “comprise(s),” “include(s),” “having,” “has,”“contain(s),” and variants thereof, are intended to be open-endedtransitional phrases, terms, or words that do not preclude thepossibility of additional acts or structure.

As used herein, the term “polymer” may refer to a polymeric compoundprepared by polymerizing monomers, whether of the same or a differenttype. The generic term “polymer” embraces the terms “homopolymer,”“copolymer”, and the like.

Acrylic copolymers prepared by sequential polymerization of polymersegments from various monomers are provided. In certain embodiments, thecopolymers contain a first reactive segment at a polymer chain end andat least one other or a second segment at another polymer chain end. Thefirst reactive segment includes at least one functional group that iscapable of undergoing a crosslinking reaction. The second segment mayalso include at least one functional group that is capable of undergoinga crosslinking reaction. The reactive segments have controlled size andplacement for tailored properties. For example, by selectively placingfunctional groups in desirable positions on a polymer molecule, polymersthat yield pressure sensitive adhesives that exhibit enhanced balancebetween cohesion and adhesion can be produced. In certain embodimentsthe polymers also include a third segment which is located between thefirst reactive segment and the second segment. The third segment mayinclude at least one reactive functionality and/or a non-reactivefunctionality. Also provided are adhesive compositions based upon thevarious polymers, and methods of preparing the polymers.

High modulus elastomers and high strength adhesives typically display aconstant modulus as a function of temperature. Conversely, highlyextensible, tough elastomers, and high tack and peel adhesives oftenhave a degree of viscous liquid character. One route to this behavior isthrough control of crosslink density via placement of reactivefunctionalities in specific segments of the polymer. Placing reactivefunctionalities in segments adjacent to the polymer end groups yieldshigh modulus and high strength upon crosslinking. Placing the reactivefunctionalities in the central segment(s) of the polymer yieldssignificant viscous liquid character. As described herein, the presentsubject matter provides strategies for controlling the structure andarchitecture of polymers and thereby enabling production of compositionshaving specific and desired characteristics.

Polymers and Crosslinkable Compositions

Generally, the present subject matter provides an acrylic polymer havinga first reactive segment that includes at least one monomer having afunctional group selected from the group consisting of a UV activefunctional group, a reactive functional group, a non-reactive functionalgroup, and combinations thereof, and a second segment that includes atleast one monomer having a functional group selected from the groupconsisting of a reactive functional group, a non-reactive functionalgroup, and combinations thereof. The reactive functionalities in thefirst reactive segment and the second segment may be the same ordifferent from one another. The non-reactive functionalities in thefirst reactive segment and the second segment may be the same ordifferent from one another. A wide array of reactive functionalities canbe included in the first reactive segment and second segment.

The first and second reactive segments are defined by (i) the type ofmonomers (i.e., UV active, reactive, and non-reactive monomers) presentin the particular segment and (ii) the ratio of the non-reactivemonomers in each segment. The present subject matter provides an acrylicpolymer and/or a pressure sensitive adhesive (PSA) comprising orconsisting of, amongst other features, a triblock acrylic copolymerhaving a {(A)(B)(C)}-{(B)(C)}-{(C)(B)(A)} structure or a{(A)(B)(C)}-{(C)}-{(C)(B)(A)} structure, or a {(A)(C)}-{(C)}-{(C)(A)}structure, where A represents the at least one monomer having a UVfunctional group, B represents the at least one monomer having areactive functional group, and C represents the at least one monomerhaving a non-reactive functional group. And {(A)(B)(C)} and {(A)(C)}represent the first reactive segment(s) while {(B)(C)} and {(C)}represent the second reactive segment(s). That is, the first reactivesegment(s) includes a UV active monomer, a reactive monomer, and anon-reactive monomer or the first reactive segment(s) includes a UVactive monomer and a non-reactive monomer, while the second reactivesegment includes a reactive monomer and a non-reactive monomer or thesecond reactive segment includes only non-reactive monomers. The atleast one monomer having a UV active functional group is about 10% orless, or about 5% or less, or about 4% or less, or about 3% or less byweight of the total polymer weight. The at least one monomer having areactive functional group in the first reactive segment and the at leastone monomer having a reactive functional group in the second reactivesegment may be the same type of monomer(s) or different type ofmonomer(s). The at least one monomer having a non-reactive functionalgroup in the first reactive segment and the at least one monomer havinga non-reactive functional group in the second reactive segment may bethe same type of monomer(s) or different type of monomer(s). The firstreactive segment(s) comprises 40% or less, 30% or less, 20% or less, 10%or less, 5% or less, or 3% or less of the total polymer molecularweight. The first reactive segment(s) include about 40% to about 99%, orabout 45% to about 99%, or about 50% to about 99%, or about 55% to about99%, or about 60% to about 99%, or about 65% to about 99%, or about 70%to about 99%, or about 75% to about 99%, or about 80% to about 99%, orabout 85% to about 99%, or about 90% to about 99%, or about 95% to about99% by weight of one or more non-reactive monomers. The first reactivesegment(s) include about 40% to about 99%, or about 45% to about 99%, orabout 50% to about 99%, or about 55% to about 99%, or about 60% to about99%, or about 65% to about 99%, or about 70% to about 99%, or about 75%to about 99%, or about 80% to about 99%, or about 85% to about 99%, orabout 90% to about 99%, or about 95% to about 99% by weight of one ormore monomers of the second reactive segment.

The present subject matter provides an acrylic polymer and/or a pressuresensitive adhesive (PSA) comprising or consisting of, amongst otherfeatures, a diblock acrylic copolymer having a {(A)(B)(C)}-{(B)(C)}structure or a {(A)(C)}-{(C)} structure, where A represents the at leastone monomer having a UV functional group, B represents the at least onemonomer having a reactive functional group, and C represents the atleast one monomer having a non-reactive functional group. And{(A)(B)(C)} and {(A)(C)} represent the first reactive segment(s) while{(B)(C)} and {(C)} represent the second reactive segment(s). That is,the first reactive segment(s) includes a UV active monomer, a reactivemonomer, and a non-reactive monomer or the first reactive segment(s)includes a UV active monomer and a non-reactive monomer, while thesecond reactive segment includes a reactive monomer and a non-reactivemonomer or the second reactive segment includes only non-reactivemonomers. The at least one monomer having a UV active functional groupis about 10% or less, or about 5% or less, or about 4% or less, or about3% or less by weight of the total polymer weight. The at least onemonomer having a reactive functional group in the first reactive segmentand the at least one monomer having a reactive functional group in thesecond reactive segment may be the same type of monomer(s) or differenttype of monomer(s). The at least one monomer having a non-reactivefunctional group in the first reactive segment and the at least onemonomer having a non-reactive functional group in the second reactivesegment may be the same type of monomer(s) or different type ofmonomer(s). The first reactive segment(s) comprises 40% or less, 30% orless, 20% or less, 10% or less, 5% or less, or 3% or less of the totalpolymer molecular weight. The first reactive segment(s) include about40% to about 99%, or about 45% to about 99%, or about 50% to about 99%,or about 55% to about 99%, or about 60% to about 99%, or about 65% toabout 99%, or about 70% to about 99%, or about 75% to about 99%, orabout 80% to about 99%, or about 85% to about 99%, or about 90% to about99%, or about 95% to about 99% by weight of one or more non-reactivemonomers. The first reactive segment(s) include about 40% to about 99%,or about 45% to about 99%, or about 50% to about 99%, or about 55% toabout 99%, or about 60% to about 99%, or about 65% to about 99%, orabout 70% to about 99%, or about 75% to about 99%, or about 80% to about99%, or about 85% to about 99%, or about 90% to about 99%, or about 95%to about 99% by weight of one or more monomers of the second reactivesegment.

As used herein, the term “reactive functional group” refers to afunctional group that is capable of reacting with another functionalgroup that is not UV-activatable. Stated differently, as used herein,the term “reactive functional group” refers to a functional group thatis crosslinkable but is not UV-activatable. Non-limiting examples ofreactive functional groups include hydroxyl, carboxyl, carbonyl,carbonate ester, isocyanate, epoxy, vinyl, amine, amide, imide,anhydride, mercapto (thiol), acid, acrylamide, acetoacetyl groups,alkoxymethylol, cyclic ether groups, and combinations thereof.

In another embodiment of the subject matter, there is provided acrosslinkable composition comprising at least one acrylic copolymerhaving a first reactive segment of controlled size and position and atleast one other or second segment of controlled size and position. Thefirst reactive segment comprises at least one monomer having afunctional group selected from the group consisting of a UV activefunctional group, a reactive functional group, a non-reactive functionalgroup, and combinations thereof. The other or second segment comprisesat least one monomer having a functional group selected from the groupconsisting of a reactive functional group, a non-reactive functionalgroup, and combinations thereof. The functional groups of the firstreactive segment and the second segment are capable of undergoingcrosslinking reactions. The acrylic copolymer of the crosslinkablecomposition may in certain embodiments also comprise a third polymericsegment. The third polymeric segment may include a reactivefunctionality and/or a non-reactive functionality. Additional aspects asdescribed in conjunction with the previously described embodiments ofthe acrylic copolymers are included in the examples described herein.

In certain embodiments, the acrylic copolymers may include at least onemonomer having a non-reactive functional group. The at least one monomerhaving a non-reactive functional group may be derived from acrylates,methacrylates, or mixtures thereof. The acrylates include C₁ to aboutC₂₀ alkyl, aryl or cyclic acrylates such as methyl acrylate, ethylacrylate, phenyl acrylate, butyl acrylate, 2-ethylhexyl acrylate,n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate, n-nonyl acrylate,isobornyl acrylate, 2-propyl heptyl acrylate, isodecyl acrylate,isostearyl acrylate and the like. These moieties typically contain fromabout 3 to about 20 carbon atoms, and in one embodiment about 3 to about8 carbon atoms. The methacrylates include C₁ to about C₂₀ alkyl, aryl orcyclic methacrylates such as methyl methacrylate, ethyl methacrylate,butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate,isobornyl methacrylate, isooctyl methacrylate, and the like. Thesemoeties typically contain from about 4 to about 20 carbon atoms, and inone embodiment about 3 to about 10 carbon atoms.

In certain embodiments, the acrylic polymers contemplated herein exhibitrelatively narrow ranges of molecular weight and thus have relativelylow polydispersity values. Typically, the polymers exhibitpolydispersity (Pdi) values of greater than 1.0, or greater than 1.5, orgreater than 2.0, or greater than 2.5, or greater than 3.0, or greaterthan greater than 3.5, or greater than 4.0. In certain embodiments, thepolymers contemplated herein exhibit polydispersity (Pdi) values of lessthan 4.0, or less than 3.5, or less than 3.0, or less than 2.5, or lessthan 2.0. In certain embodiments, the polymers exhibit polydispersitiesof less than 1.5, or as low as about 1.4.

In certain embodiments, the polymers typically have a number averagemolecular weight (Mn) of from about 5,000 g/mol to about 150,000 g/mol,or from about 10,000 g/mol to about 150,000 g/mol, or from about 40,000g/mol to about 150,000 g/mol, or from about 50,000 g/mol to about110,000 g/mol, or from about 30,000 g/mol to about 80,000 g/mol, or fromabout 10,000 g/mol to about 30,000 g/mol.

In certain embodiments, the polymers typically have a weight averagemolecular weight (Mw) of from about 50,000 g/mol to about 1,000,000g/mol, or from about 100,000 g/mol to about 500,000 g/mol, or from about100,000 g/mol to about 250,000 g/mol. However, it will be appreciatedthat the subject matter includes polymers having molecular weightsand/or polydispersity values greater than or less than the values notedherein.

The average molecular (M_(w)) weight and polydispersity (PDI) weredetermined by gel permeation chromatography (GPC). The samples wereevaluated on a Waters Acquity Advance Polymer Chromatography system. Theeluent used was TetraHydroFuran (THF) containing stabilizer.Measurements were carried out at 35° C. Separation was carried out usingthe columns HSP Gel RT MB-M (1,000 to 4,000,000 Dalton range), HSP GelHT MB-L/M (500-4,000,000 Dalton range), and HSP Gel HR 1.0 (100-1,000Dalton range). The sample concentration was 2 g/I, the flow rate of 0.7ml/min. Measurements were carried out against polystyrene standards.

Reactive Segments

In certain embodiments, the first reactive segment of the acrylicpolymer may include a copolymer derived from one or more of the monomersof the second segment and at least one polymerizable comonomer having acrosslinkable functionality, the crosslinkable functionality selectedfrom the group consisting of a UV active functional group, a reactivefunctional group, and combinations thereof.

In certain embodiments, the first reactive segment of the acrylicpolymer may include a copolymer derived from at least one monomer havinga non-reactive functional group and at least one polymerizable comonomerhaving a crosslinkable functionality, the crosslinkable functionalityselected from the group consisting of a UV active functional group, areactive functional group, and combinations thereof.

In certain embodiments, the at least one monomer having a non-reactivefunctional group may include at least one monomer derived from theformula (I):

-   -   where R₃ is H or CH₃ and R₄ is a branched or unbranched,        saturated alkyl group having 4 to 14 carbon atoms.

In certain embodiments, the at least one monomer having a reactivefunctional group may include at least one functionalized monomer derivedfrom the formula (I):

-   -   where R₃ is H or CH₃ and R₄ is a branched or unbranched,        saturated alkyl group having 4 to 14 carbon atoms. The at least        one functionalized monomer of the reactive functional group may        include a crosslinkable functional group selected from the group        consisting of hydroxyl, carboxyl, carbonyl, carbonate ester,        isocyanate, epoxy, vinyl, amine, amide, imide, anhydride,        mercapto (thiol), acid, acrylamide, acetoacetyl groups,        alkoxymethylol, cyclic ether groups, and combinations thereof.

In certain embodiments, the at least one monomer having a reactivefunctional group may be derived from the formula (II):

-   -   where R is H or CH₃ and X includes a functional group capable of        crosslinking. The crosslinkable functional group may include at        least one functional group selected from the group consisting of        hydroxyl, carboxyl, carbonyl, carbonate ester, isocyanate,        epoxy, vinyl, amine, amide, imide, anhydride, mercapto (thiol),        acid, acrylamide, acetoacetyl groups, alkoxymethylol, cyclic        ether groups, and combinations thereof.

In certain embodiments, the first reactive segment of the acrylicpolymer may include a copolymer derived from one or more of the monomersof the second segment and at least one monomer having a reactivefunctional group. The at least one monomer having a reactive functionalgroup may be derived from the formula (II):

-   -   where R is H or CH₃ and X includes a functional group capable of        crosslinking. The crosslinkable functional group may include at        least one functional group selected from the group consisting of        hydroxyl, carboxyl, carbonyl, carbonate ester, isocyanate,        epoxy, vinyl, amine, amide, imide, anhydride, mercapto (thiol),        acid, acrylamide, acetoacetyl groups, alkoxymethylol, cyclic        ether groups, and combinations thereof.

Hydroxy functional monomers include, for example, hydroxy ethyl(meth)acrylate, hydroxy isopropyl (meth)acylate, hydroxy butyl(meth)acrylate and the like.

Epoxy functional monomers include, for example, glycidyl methacrylateand glycidal acrylate. In certain embodiments, a particularly epoxyfunctional monomer is commercially available under the designation S-100from Synasia. That monomer is 3, 4 epoxycydohexylmethyl methacrylate,[CAS 82428-30-6], having a chemical formula C₁₁H₁₆O₃ and a molecularweight of 196.2.

The acid containing monomers include, for example, unsaturatedcarboxylic acids containing from 3 to about 20 carbon atoms. Theunsaturated carboxylic acids include, among others, acrylic acid,methacrylic acid, itaconic acid, beta carboxy ethyl acrylate,mono-2-acroyloxypropyl succinate, and the like. It is contemplated thatphosphoric acids may be used.

Anhydride containing monomers include, for example, maleic anhydride,itaconic anhydride, citraconic anhydride and the like.

The acrylamides include, for example, acrylamide and its derivativesincluding the N-substituted alkyl and aryl derivatives thereof. Theseinclude N-methyl acrylamide, N,N-dimethyl acrylamide, t-octyl acrylamideand the like. The methacrylamides include methacrylamide and itsderivatives including the N-substituted alkyl and aryl derivativesthereof.

Vinyl groups include, for example, vinyl esters, vinyl ethers, vinylamides, and vinyl ketones. The vinyl esters include vinyl acetate, vinylpropionate, vinyl butyrate, vinyl valerate, vinyl versitate, vinylisobutyrate and the like. The vinyl ethers include vinyl ethers having 1to about 8 carbon atoms including ethylvinyl ether, butylvinyl ether,2-ethylhexylvinyl ether and the like. The vinyl amides include vinylamides having 1 to about 8 carbon atoms including vinyl pyrrolidone, andthe like. The vinyl ketones include vinyl ketones having 1 to about 8carbon atoms including ethylvinyl ketone, butylvinyl ketone, and thelike.

In another embodiment, the first reactive segment of the acrylic polymermay include a copolymer derived from one or more of the monomers of thesecond segment and at least one polymerizable comonomer having acrosslinkable functionality, the crosslinkable functionality selectedfrom the group consisting of a UV active functional group, a reactivefunctional group, and combinations thereof. The at least onepolymerizable comonomer having a reactive functional group includes atleast one functionalized monomer derived from the formula (I):

-   -   where R₃ is H or CH₃ and R₄ is a branched or unbranched,        saturated alkyl group having 4 to 14 carbon atoms. The at least        one functionalized monomer may include a crosslinkable        functional group selected from the group consisting of hydroxyl,        carboxyl, carbonyl, carbonate ester, isocyanate, epoxy, vinyl,        amine, amide, imide, anhydride, mercapto (thiol), acid,        acrylamide, acetoacetyl groups, alkoxymethylol, cyclic ether        groups, and combinations thereof.

In particular embodiments, the at least one polymerizable comonomerhaving a crosslinkable functionality includes a UV active functionalgroup. Although a wide array of UV active functional groups canpotentially be used, in certain embodiments the UV active functionalgroup is selected from benzophenones, double bonds, and combinationsthereof.

In many embodiments, the UV active functional group is represented byFormula (III) as follows:

-   -   in which R₁ and R₂ is each independently an organic radical        selected from the group of methyl, aryl, and alkyl. In many        embodiments, R₁ and/or R₂ is an aromatic or substituted aromatic        group. In certain embodiments, R₁ and/or R₂ is a phenyl or        substituted phenyl group. In particular embodiments, the UV        active functional group includes acetophenone, an acetophenone        derivative, benzophenone, a benzophenone derivative,        anthraquinone, an anthraquinone derivative, benzile, a benzile        derivative, thioxanthone, a thioxanthone derivative, xanthone, a        xanthone derivative, a benzoin ether, a benzoin ether        derivative, an alpha-ketol, an alpha-ketol derivative, and        combinations thereof.

In many embodiments, the UV active functional group is a UV-activatablegroup, i.e., decomposes or is otherwise triggered to form reactivespecies that activate crosslinking of polymers.

It is also contemplated that the UV active functional group couldinclude or be based upon aromatic sulfonyl chlorides, photoactiveoximes, and azo-type initiators.

Furthermore, in many embodiments the UV active functional group can beone or more benzophenone, benzophenone derivatives, double bonds, and/orcombinations of these with other UV active functional groups. It will beunderstood that the present subject matter is not limited to any ofthese noted UV active functional groups.

In still additional embodiments, the UV active functional group includesone or more photoinitiators.

Additionally, the present subject matter may include the use of one ormore other UV active functional groups instead of, or in combinationwith the UV active functional groups described herein.

In certain embodiments, the UV active functional groups are incorporatedalong end segment(s) of the polymer. In particular embodiments, the UVactive functional group(s) are entirely incorporated along an endsegment or end segments with the reactive functional group(s) and/or thenon-reactive functional group(s) randomly incorporated within the sameend segment(s) that comprise 40% or less of the total polymer molecularweight, such that the remaining 60% or more of the polymer or polymerinterior segment(s) is free of UV functional groups and includesreactive functional group(s) and/or non-reactive functional group(s)randomly incorporated therein.

In other particular embodiments, the UV active functional group(s) areentirely incorporated along an end segment or end segments with thereactive functional group(s) and/or the non-reactive functional group(s)randomly incorporated within the same end segment(s) that comprise 30%or less of the total polymer molecular weight, such that the remaining70% or more of the polymer or polymer interior segment(s) is free of UVfunctional groups and includes reactive functional group(s) and/ornon-reactive functional group(s) randomly incorporated therein.

In still other particular embodiments, the UV active functional groupsare entirely incorporated along an end segment or end segments with thereactive functional group(s) and/or the non-reactive functional group(s)randomly incorporated within the same end segment(s) that comprise 20%or less of the total polymer molecular weight, such that the remaining80% or more of the polymer or polymer interior segment(s) is free of UVfunctional groups and includes reactive functional group(s) and/ornon-reactive functional group(s) randomly incorporated therein.

And, in still other particular embodiments, the UV active functionalgroup(s) are entirely incorporated along an end segment or end segmentswith the reactive functional group(s) and/or the non-reactive functionalgroup(s) randomly incorporated within the same end segment(s) thatcomprise 10% or less of the total polymer molecular weight, such thatthe remaining 90% or more of the polymer or polymer interior segment(s)is free of UV functional groups and includes reactive functionalgroup(s) and/or non-reactive functional group(s) randomly incorporatedtherein.

In yet another particular embodiment, the UV active functional groupsare entirely incorporated along an end segment or end segments with thereactive functional group(s) and/or the non-reactive functional group(s)randomly incorporated within the same end segment(s) that comprise 5% orless of the total polymer molecular weight, such that the remaining 95%or more of the polymer or polymer interior segment(s) is free of UVfunctional groups and includes reactive functional group(s) and/ornon-reactive functional group(s) randomly incorporated therein.

And, in still another more particular embodiment, the UV activefunctional groups are entirely incorporated along an end segment or endsegments with the reactive functional group(s) and/or the non-reactivefunctional group(s) randomly incorporated within the same end segment(s)that comprise 3% or less of the total polymer molecular weight, suchthat the remaining 97% or more of the polymer or polymer interiorsegment(s) is free of UV functional groups and includes reactivefunctional group(s) and/or non-reactive functional group(s) randomlyincorporated therein.

Methods

The present subject matter also provides, in another embodiment, amultiple step polymerization process for making a crosslinkable acryliccopolymer having a first reactive segment with polymerization processfor making a crosslinkable acrylic copolymer having a first reactivesegment having one or more functional groups selected from the groupconsisting of a UV active functional group, a reactive functional group,a non-reactive functional group, and combinations thereof provided by atleast one monomer. Preferably, the monomer is an acrylic monomer. Asecond segment is added to the first segment to form the acryliccopolymer. The second segment may contain one or more functional groupsselected from the group consisting of a reactive functional group, anon-reactive functional group, and combinations thereof and is misciblewith the first reactive segment.

As used herein, the term “molecularly miscible” means a compound ormixture of compounds that exhibit properties in the bulk state that canbe observed and/or measured by one of ordinary skill in the art and areindicative of single phase behavior or a single phase polymer. The term“single phase behavior” refers to behavior or physical properties thatare uniform or substantially so. With respect to the acrylic copolymer,the observation of a single Tg is indicative of polymer segmentmiscibility. The single Tg is intermediate between those of theconstituent polymer segments and varies monotonically between thesevalues as the relative amounts of each segment changes. In contrast tosingle phase behavior evidenced by a molecularly miscible compound ormixture of compounds, at a given temperature, a phase separated compounddemonstrates multiple, independent sets of properties that areattributable to the different phases of matter present therein. Suchsets of properties include, without limitation, Tg, solubilityparameters, refractive index, and physical state/phase of matter.Accordingly, the term “phase separated” is defined as two or moresubstances which are molecularly segregated due to one or more chemicaland/or physical properties dependent upon, without limitation, polarity,molecular weight, relative amounts of the polymer segments, and Tg(phase of matter).

Evidence of immiscibility/incompatibility between blocks/segments of ablock copolymer, such as an ABA block copolymer, can be confirmed viarheological measurements such as Dynamic Mechanical Analysis (DMA) orDifferential Scanning calorimetry (DSC) and the microstructuredetermined from microscopy. Miscible polymers exhibit no heterogeneity(i.e., are single phase polymers) in their microstructure. The degree ofmiscibility/compatibility of a polymer blend can be simply determined bymeasuring the glass transition temperature(s) in a DMA or DSC can. Thepresence of two Tgs indicates immiscibility, while the presence of onlya single Tg indicates a miscible blend. For block copolymers withmutually incompatible blocks, the microdomains formed by the differentblocks exhibit separate/different Tgs, and for incompatible blockcopolymers separate Tg values are also observed in the DMA and/or DSCplots. For example, for typical styrenic and acrylic ABA blockcopolymers, the hard A block and the soft B block have sufficientlydifferent solubility parameters such that they are not thermodynamicallycompatible with each other. As a result, block copolymer-based adhesiveshave a unique microphase-separated morphology, where A blocks form ahard phase embedded in a soft, continuous phase composed of B blocks.That is, a result of the frequent immiscibility/incompatibility of thetwo types of blocks present in ABA block copolymers, block copolymersgenerally exhibit two distinct glass transitions (a DMA bimodal tan 5curve) at temperatures very close to those of the correspondinghomopolymers. The presence of acid, however, in block copolymers such asP(MMA/MAA)-PBA-P(MMA/MAA) raises the Tg of the end block and alsoenhances the phase separation between the soft acrylate and the hardPMMA domains. Therefore, block copolymers can exhibit morphologies whichrange from two-phase segregated materials to single-phase homogeneousmaterials.

The acrylic polymers contemplated herein are architectured polymersformed via a controlled free-radical process including selectingmonomers that form homogeneous (single phase) acrylic block copolymersas evidenced by the presence of a single Tg peak shown in FIG. 13,indicative of a homogeneous (single phase) polymer prior tocrosslinking.

As used herein, the term “homogeneous polymer” is a block copolymerhaving substantially one morphological phase in the same state. Forexample, a block copolymer of two or more segments where one segment ismiscible with another segment is said to be homogeneous in the liquidstate. Such morphology is determined using atomic force microscopy (AFM)or scanning electron microscopy (SEM). By miscible is meant that theblock copolymer of two or more segments exhibits single-phase behaviorfor the glass transition temperature, e.g. the Tg would exist as asingle, sharp transition temperature on a dynamic mechanical thermalanalyzer (DMTA) trace of tan 5 (the ratio of loss modulus to the storagemodulus) versus temperature, as shown in the plots of FIG. 13. Bycontrast, two separate transition temperatures would be observed for animmiscible block copolymer, typically corresponding to the temperaturesfor each of the individual segments of the block copolymer. Thus a blockcopolymer is miscible when there is one Tg indicated on the DMTA trace.A miscible block copolymer is homogeneous, while an immiscible blockcopolymer is heterogeneous.

In contrast, the term “heterogeneous polymer” means a block copolymerhaving two or more morphological phases in the same or different state.For example, a block copolymer of two segments where one segment formsdiscrete packets dispersed in a matrix of another segment is said to beheterogeneous. Also a heterogeneous polymer is defined to includeco-continuous segments where the block copolymer components areseparately visible, but it is unclear which is the continuous phase andwhich is the discontinuous phase. Such morphology is determined usingscanning electron microscopy (SEM) or atomic force microscopy (AFM). Bycontinuous phase is meant the matrix phase in a heterogeneous blockcopolymer. By discontinuous phase is meant the dispersed phase in aheterogeneous block copolymer.

DMA was performed on a TA Instruments AR2000 rheometer fitted withparallel plate clamps. 1.0 mm thick samples were placed in the clamp andannealed at 70° C. for 10 minutes to ensure good adhesion. The sampleswere then cooled to −60° C. to begin a temp sweep to 150° C. at a ramprate of 3° C./min. During the temp ramp, the samples were oscillated ata frequency of 10 rad/sec.

Representative and non-limiting examples of ranges of glass transitiontemperatures (Tg) for the acrylic polymers and/or pressure sensitiveadhesives of the present subject matter are from about 15° C. to about−115° C., or from about 0° C. to about −80° C., and/or from about −35°C. to about −60° C.

Controlled Radical Polymerization

With conventional free-radical polymerization, polymers are terminatedwhen the reactive free radical end group is destroyed via termination orchain transfer reactions. The termination and chain transfer processesare typically irreversible and yield a polymer that is inactive. Theresult of this is a broad molecular weight distribution and littlecontrol over the distribution of monomers in the polymer backbone.“Living” polymerization enables control over the polymer architecture,which includes molecular weight, molecular weight distribution(polydispersity), functionality, and composition. In livingpolymerization strategies, the occurrence of premature termination isminimized, and molecular weight proceeds linearly with time until allmonomer is consumed or intentionally terminated. Controlled radicalpolymerizations involve reversible radical processes in whichirreversible termination and chain transfer are largely absent.Controlled free radical polymerization includes three fundamentaltechniques, atom transfer radical polymerization (ATRP), reversibleaddition-fragmentation chain transfer (RAFT), and stable free radicalpolymerization (SFRP) (of which nitroxide mediated polymerization (NMP)is a subset). RAFT and SFRP are particularly useful methods because oftheir tolerance to a wide array of functional groups and theirefficiency and versatility in producing controlled radical polymerizedpolymers.

The acrylic copolymers of the subject matter are prepared using any ofthe controlled radical polymerization processes, which includeatom-transfer radical polymerization (ATRP); rapidaddition-fragmentation chain transfer (RAFT); and stable free radicalpolymerization (SFRP). Nitroxide-mediated polymerization (NMP) is anexample of an SFRP process.

ATRP involves the chain initiation of free radical polymerization by ahalogenated organic species in the presence of a metal halide species.The metal has a number of different oxidation states that allows it toabstract a halide from the organohalide, creating a radical that thenstarts free radical polymerization. After initiation and propagation,the radical on the chain active chain terminus is reversibly terminated(with the halide) by reacting with the catalyst in its higher oxidationstate. A simplified mechanism for reversible activation-deactivation ofpolymer chains during ATRP is shown in Scheme 1. Thus the redox processgives rise to an equilibrium between dormant (polymer-halide) and active(polymer-radical) chains. The equilibrium is designed to heavily favorthe dormant state, which effectively reduces the radical concentrationto sufficiently low levels to limit bimolecular coupling.

The initiator in ATRP is usually a low molecular weight activatedorganic halide (RX, R=activated alkyl, X=chlorine, bromine, iodine).However, organic pseudohalides (e.g., X=thiocyanate, azide) andcompounds with weak N-X (e.g., N-bromosuccinimide) or S-X (e.g.,sulfonyl halides) may be used. ATRP can be mediated by a variety ofmetals, including Ti, Mo, Re, Fe, Ru, Os, Rh, Co, Ni, Pd and Cu.Complexes of Cu offer the most efficient catalysts in the ATRP of abroad range of monomer in diverse media. Commonly used nitrogen-basedligands used in conjunction with Cu ATRP catalysts include derivativesof bidentate bipyridine and pyridine imine, tridentatediethylenetriamine and tetradentate tris[2-aminoethylene]amine andtetraazacyclotetradecane.

Controlled polymerization by RAFT occurs via rapid chain transferbetween growing polymer radicals and dormant polymer chains. Afterinitiation, the control agent becomes part of the dormant polymer chain.The key mechanistic features of RAFT are illustrated in Scheme 2. CommonRAFT agents contain thiocarbonyl-thio groups, and include, for example,dithioesters, dithiocarbamates, trithiocarbonates and xanthenes.Examples of useful RAFT agents include those described in “The Chemistryof Radical Polymerization”, Graeme Moad & David H. Solomon, 2^(nd) rev.ed., 2006, Elsevier, p. 508-514, which is incorporated by referenceherein.

Initiation and radical-radical termination occur as in conventionalradical polymerization. In the early stages of the polymerization,addition of a propagating radical (Pn^(·)) to the thiocarbonylthiocompound followed by fragmentation of the intermediate radical givesrise to a polymeric thiocarbonylthio compound and a new radical (R^(·)).Reaction of the radical (R^(·)) with monomer forms a new propagatingradical (Pm^(·)). A rapid equilibrium between the active propagatingradicals (Pn^(·) and Pm^(·)) and the dormant polymeric thiocarbonylthiocompounds provides equal probability for all chains to grow and allowsfor the production of narrow dispersity polymers.

SFRP, and in particular, NMP achieves control with dynamic equilibriumbetween dormant alkoxyamines and actively propagating radicals. The useof nitroxides to mediate (i.e., control) free radical polymerization hasbeen developed extensively. Many different types of nitroxides have beendescribed and there are many methods for producing nitroxides in-situ.Regardless of the nitroxide or its method of generation, the keymechanistic feature of NMP is reversible coupling of the nitroxide(i.e., R2NO) to a growing polymer chain radical (P^(·)) as shown inScheme 3.

Examples of useful NMP agents include those described in “The Chemistryof Radical Polymerization”, Graeme Moad & David H. Solomon, 2^(nd) rev.ed., 2006, Elsevier, p. 473-475, which is incorporated by referenceherein. An example of a commercially available NMP agent isBlocBuilder®, an alkoxyamine compound that acts an initiator and controlagent, available from Arkema.

The methods for forming the acrylic polymers contemplated herein may useone or more polymerization catalysts. The polymerization catalyst canbe, for example, organic tin compounds, metal complexes, amine compoundsand other basic compounds, organic phosphate compounds, and organicacids. Examples of the organic tin compounds include dibutyltindilaurate, dibutyltin maleate, dibutyltin phthalate, stannous octoate,dibutyltin methoxide, dibutyltin diacetylacetate and dibutyltindiversatate. Examples of metal complexes are titanate compounds such astetrabutyl titanate, tetraisopropyl titanate, and tetraethanolaminetitanate; metal salts of carboxylic acids, such as lead octoate, leadnaphthoate, and cobalt naphthoate; and metal acetylacetonate complexessuch as aluminum acetylacetonate complex and vanadium acetylacetonatecomplex. The amine compounds and other basic compounds include, forexample aminisilanes such as γ-aminopropyl trimethoxysilane andγ-aminopropyltriethoxysilane; quaternary ammonium salts such astetramethylammonium chloride and benzalkonium chloride; andstraight-chain or cyclic tertiary amines or quaternary ammonium saltseach containing plural nitrogen atoms. The organic phosphate compoundsinclude monomethyl phosphate, di-n-butyl phosphate and triphenylphosphate. Examples of organic acid catalysts include alkyl sulfonicacids such as methane sulfonic acid, aryl sulfonic acids such asp-toluene sulfonic acid, benzene sulfonic acid, styrene sulfonic acidand the like.

Adhesives

Adhesives having a wide array of properties can be formed from theacrylic polymers and/or compositions described herein. Generally, theacrylic polymers described herein are crosslinked and optionallycombined with one or more components to provide an adhesive composition.In certain embodiments, the adhesives are pressure sensitive adhesives.The polymer may be crosslinked during post curing of the adhesive toincrease the cohesive strength of the pressure sensitive adhesive. Thiscan be achieved via covalent crosslinking such as heat, actinic orelectron beam radiation, or metal based ionic crosslinking betweenfunctional groups. Table 1 below lists representative examples ofcrosslinkers for various functional groups of the segmented polymer.

TABLE 1 Crosslinkers Functional Group of Segmented Polymer CrosslinkerHydroxyl Isocyanate, Melamine Formaldehyde, Anhydride, Epoxy, Titaniumesters and Chelates Carboxylic acid, Aziridines, Isocyanate, MelamineFormaldehyde, phosphoric acid Anhydride, Epoxy, Carboiimides, MetalChelates, Titanium esters and Oxazolines Isocyanate Self-reactive,Carboxylic acid, Amine, Hydroxyl Vinyl Addition reaction with Siliconehydride (Meth)acrylate Amine, Mercaptan, Self-reactive with radicalcatalyst (UV, Thermal), Acetoacetate Epoxy Amine, Carboxylic acid,Phosphoric acid, Hydroxyl, Mercaptan Amine Isocyanate, Melamineformaldehyde, anhydride, epoxy, acetoacetate Mercapto (thiol)Isocyanate, Melamine formaldehyde, Anhydride, Epoxy AcetoacetateAcrylate, Amine Alkoxymethylol Acid, Hydroxyl, Thiol (Mercapto), AmineCylic Ethers Hydroxyl, Amines, Thiol (Mercapto)

Suitable polyfunctional aziridines include, for example,trimethylolpropane tris[3-aziridinylpropionate]; trimethylolpropanetris[3-(2-methylaziridinyl) propionate]; trimethylolpropanetris[2-aziridinylbutyrate]; tris(1-aziridinyl)-phosphine oxide;tris(2-methyl-1-aziridinyl)phosphine oxide;penta-erythritoltris[3-(1-aziridinyl)propionate]; and pentaerythritoltetrakis[3-(1-aziridinyl)propionate]. Combinations of more than onepolyfunctional aziridine may also be used. Examples of commerciallyavailable polyfunctional aziridines include NEOCRYL CX-100 from ZenecaResins, believed to be trimethylolpropatentris[3-(2-methylaziridinyl)-propanoate], and Xama-2, Xama-7 and Xama-220from Bayer Material Science.

Multifunctional aziridine amides which have the general formula (IV):

-   -   wherein R can be either an alkylene or aromatic group and R′ can        be a hydrogen or alkyl group and x is at least 2 may be used.        Examples of suitable multifunctional aziridine amides include        1,1′-(1,3-phenylenedicarbonyl)bis[2-methyl aziridine];        2,2,4-trimethyladipoyl bis [2-ethyl aziridine]; 1,1′-azelaoyl        bis [2-methyl aziridine]; and        2,4,6-tris(2-ethyl-1-aziridinyl)-1,3,5 triazine.

Metal chelate crosslinking agents may be compounds prepared bycoordinating multivalent metals such as Al, Fe, Zn, Sn, Ti, Sb, Mg and Vwith acethylacetone or ethyl acetoacetonate.

Among the isocyanate crosslinking agents that can be used are aromatic,aliphatic and cycloaliphatic diisocyanates and triisocyanates. Examplesinclude 2,4-toluene diisocyanate, m-phenylene diisocyanate,4-chloro-1,3-phenylene diisocyanate, 3,3′-dimethyl-4,4′-diphenylenediisocyanate, 4,4′-diphenylene diisocyanate, xylene diisocyanate,1,6-hexamethylene diisocyanate, 1,10-decamethylene diisocyanate,1,4-cyclohexylene diisocyanate, 4,4′methylene bis(cyclohexylisocyanate), 1,5-tetrahydronaphthalene diisocyanate, paraxylylenediisocyanate, durene diisocyante, 1,2,4-benzene diisocyanate, isoformdiisocyanate, 1,4-tetramethylxylene diisocyanate, 1,5-naphthalenediisocyanate, or their reactants with polyol such as trimethylolpropane.

Other useful crosslinking agents include monomeric and polymericmelamine crosslinkers, such as Cymel 303 and 370 available from Cytec.

The crosslinking agent is typically used at a level from about 0.05% toabout 5%, or from about 0.075% to about 2%, or from about 0.1% to about1.5% by weight of adhesive solids.

Anhydride functional segmented polymers may be converted to silanes viaa post polymerization reaction with amino-, mercapto- orhydroxyl-functional silanes. Examples of amino group-containingalkoxysilanes having a primary amino group alone as a reactive groupinclude aminoalkyltrialkoxysilanes such as aminomethyltrimethoxysilane,aminomethyltriethoxysilane, β-amino-ethyltrimethoxysilane,β-aminoethyltriethoxysilane, γ-aminopropyltrimeth-oxysilane,γ-aminopropyltriethoxysilane, γ-aminopropyltripropoxysilane,γ-aminopropyltriisopropoxysilane, and γ-aminopropyltributoxysilane;(aminoalkyl)-alkyldialkoxysilanes such asβ-aminoethylmethyldimethoxysilane, γ-amino-ethylmethyldiethoxysilane,γ-aminopropylmethyldimethoxysilane, γ-aminopropyl-methyldiethoxysilane,and γ-aminopropylmethyldipropoxysilane; and correspondingaminoalkyldialkyl(mono)alkoxysilanes.

Examples of amino group-containing alkoxysilanes having a primary aminogroup and a secondary amino group as reactive groups includeN-(aminoalkyl)aminoalkyltrialkoxysilanes such asN-β-(aminoethyl)-γ-aminopropyl-trimethoxysilane andN-β-(aminoethyl)-γ-aminopropyltriethoxysilane; andN-(aminoalkyl)aminoalkylalkyldialkoxysilanes such asN-β-(aminoethyl)-γ-amino-propylmethyldimethoxysilane andN-β-(aminoethyl)-γ-aminopropylmethyl-diethoxysilane.

Examples of amino group-containing alkoxysilanes having a secondaryamino group alone as a reactive group includeN-phenylamino-methyltrimethoxysilane andN-phenyl-β-aminoethyltrialkoxysilanes such asN-phenyl-β-aminoethyltrimethoxysilane andN-phenyl-β-aminoethyltriethoxysilane;N-phenyl-γ-aminopropyltrialkoxysilanes such asN-phenyl-γ-aminopropyltrimethoxysilane,N-phenyl-γ-aminopropyltriethoxysilane,N-phenyl-γ-aminopropyltripropoxysilane, andN-phenyl-γ-aminopropyltributoxysilane; correspondingN-phenylaminoalkyl(mono- or di-)alkyl(di- or mono-)alkoxysilanes; aswell as N-alkylaminoalkyltrialkoxysilanes corresponding to theabove-listed amino group-containing alkoxysilanes having a secondaryamino group substituted with phenyl group, such asN-methyl-3-aminopropyltrimethoxysilane,N-ethyl-3-aminopropyltrimethoxysilane,N-n-propyl-3-aminopropyltrimethoxysilane,N-n-butyl-aminomethyltrimethoxysilane,N-n-butyl-2-aminoethyltrimethoxysilane,N-n-butyl-3-aminopropyltrimethoxysilane,N-n-butyl-3-aminopropyltriethoxysilane, andN-n-butyl-3-aminopropyltripropoxysilane, and correspondingN-alkylaminoalkyl(mono- or di-)alkyl(di- or mono)alkoxysilanes. Othersinclude N-cyclohexylaminomethylmethyldiethoxy silane andN-cyclohexylaminomethyl-triethoxysilane.

Examples of the mercapto group-containing silanes includemercaptoalkyltrialkoxysilanes such as mercaptomethyltrimethoxysilane,mercaptomethyltriethoxysilane, β-mercaptoethyltrimethoxysilane,β-mercapto-ethyltriethoxysilane, β-mercaptoethyltripropoxysilane,β-mercaptoethyl-triisopropoxysilane, β-mercaptoethyltributoxysilane,γ-mercaptopropyl-trimethoxysilane, γ-mercaptopropyltriethoxysilane,γ-mercaptopropyltri-propoxysilane, γ-mercaptopropyltriisopropoxysilane,and γ-mercapto-propyltributoxysilane;(mercaptoalkyl)alkyldialkoxysilanes such asβ-mercaptoethylmethyldimethoxysilane,β-mercaptoethylmethyldiethoxysilane,γ-mercaptopropylmethyldimethoxysilane,γ-mercaptopropylmethyldiethoxysilane,γ-mercaptopropylmethyldipropoxysilane,β-mercaptopropylmethyldiisopropoxy-silane,γ-mercaptopropylmethyldibutoxysilane,β-mercaptopropylmethyldibutoxysilane,γ-mercaptopropylethyldimethoxy-silane,γ-mercaptopropylethyldiethoxysilane,γ-mercaptopropylethyldipropoxy-silane,γ-mercaptopropylethyldiisopropoxysilane, andγ-mercaptopropyl-ethyldibutoxysilane; and corresponding(mercaptoalkyl)dialkyl(mono)-alkoxysilanes.

Examples of hydroxyl-functional silanes include hydroxymethyltrialkoxysilanes having the formula (V):

Where R is an alkyl group and n is at least 1. The alkyl group may be alower alkyl group having 1 to 6 carbon atoms, or 1 to 3 carbon atoms.Particularly useful are the silanes in which the alkyl group is methylor ethyl, namely hydroxymethyltriethoxysilane andhydroxymethyltriethoxysilane when n is equal to 1.

The adhesives of the present subject matter may further compriseadditives such as pigments, fillers, plasticizer, diluents,antioxidants, tackifiers and the like. Pigment, if desired, is providedin an amount sufficient to impart the desired color to the adhesive.Examples of pigments include, without limitation, solid inorganicfillers such as carbon black, titanium dioxide and the like, and organicdyes. Additional inorganic fillers such as aluminum trihydrate,christobalite, glass fibers, kaolin, precipitated or fumed silica,copper, quartz, wollasonite, mica, magnesium hydroxide, silicates (e.g.feldspar), talc, nickel and calcium carbonate are also useful. Metaloxides such as aluminum trihydrate and magnesium hydroxide areparticularly useful as flame retardants.

A wide variety of tackifiers can be used to enhance the tack and peel ofthe adhesive. These include rosins and rosin derivatives includingrosinous materials that occur naturally in the oleoresin of pine trees,as well as derivatives thereof including rosin esters, modified rosinssuch as fractionated, hydrogenated, dehydrogenated, and polymerizedrosins, modified rosin esters and the like.

There may also be employed terpene resins which are hydrocarbons of theformula C₁₀H₁₆, occurring in most essential oils and oleoresins ofplants, and phenol modified terpene resins like alpha pinene, betapinene, dipentene, limonene, myrecene, bornylene, camphene, and thelike. Various aliphatic hydrocarbon resins like Escorez 1304,manufactured by Exxon Chemical Co., and aromatic hydrocarbon resinsbased on C₉, C₅, dicyclopentadiene, coumarone, indene, styrene,substituted styrenes and styrene derivatives and the like can also beused.

Hydrogenated and partially hydrogenated resins such as Regalrez 1018,Regalrez 1033, Regalrez 1078, Regalrez 1094, Regalrez 1126, Regalrez3102, Regalrez 6108, etc., produced by Eastman Chemical Company, can beused. Various terpene phenolic resins of the type SP 560 and SP 553,manufactured and sold by Schenectady Chemical Inc., Nirez 1100,manufactured and sold by Reichold Chemical Inc., and Piccolyte S-100,manufactured and sold by Hercules Corporation, are particularly usefultackifiers for the present subject matter. Various mixed aliphatic andaromatic resins, such as Hercotex AD 1100, manufactured and sold byHercules Corporation, can be used.

While the resins described above are quite useful for tackifying thecopolymers of the instant subject matter, the particular tackifyingresin and/or amount selected for a given formulation may depend upon thetype of acrylic polymer being tackified. Many resins which are known inthe prior art as being useful for tackifying acrylic based pressuresensitive adhesives can be effectively used in the practice of thepresent subject matter, although the scope of the subject matter is notlimited to only such resins. Resins described in Satas, Handbook ofPressure Sensitive Adhesive Technology, Von Nostrand Reinhold, Co, Chap.20, pages 527-584 (1989) (incorporated by reference herein) could beused.

The amount of tackifier used in the present subject matter is dependentupon the type of copolymer and tackifier used. Typically, pressuresensitive adhesive compositions prepared in accordance with the presentsubject matter will comprise from 5 to about 60% by weight total of oneor more tackifiers.

In one embodiment, the tackifier has a ring and ball softening point offrom about 100° C. to about 150° C. In one embodiment, the tackifiercomprises a terpene phenolic tackifier having a ring and ball softeningpoint of from about 110° C. to about 120° C.

In another embodiment, the added resin may serve a dual purpose. Forexample, a resin such as Wingstay L®, a butylated reaction product ofpara-cresol and dicyclopentadiene with an average molecular weight of650 produced by Eliokem, can serve both as a tackifier and anantioxidant.

In one embodiment, a low molecular weight polymeric additive isincorporated into the adhesive composition. The polymeric additive ispolymerized from monomers selected from C₁-C₂₀ alkyl and cycloalkylacrylates, C₁-C₂₀ alkyl and cycloalkyl methacrylates, free radicalpolymerizable olefinic acids, and optionally other ethylenicallyunsaturated monomers. Suitable alkyl and cycloalkyl acrylates includethe various esters of acrylic acid such as methyl acrylate, ethylacrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate,isobutyl acrylate, t-butyl acrylate, isobornyl acrylate, pentylacrylate, hexyl acrylate, octyl acrylate, iso-octyl acrylate, nonylacrylate, lauryl acrylate, stearyl acrylate, eicosyl acrylate,2-ethylhexyl acrylate, cyclohexyl acrylate, cycloheptyl acrylate, andthe like and mixtures thereof. Suitable alkyl and cycloalkylmethacrylate include the esters of methacrylic acid such as methylmethacrylate, ethyl methacrylate, propyl methacrylate, n-butylmethacrylate, t-butyl methacrylate, isobutyl methacrylate, pentylmethacrylate, hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexylmethacrylate, isobornyl methacrylate, heptyl methacrylate, cycloheptylmethacrylate, octyl methacrylate, iso-octyl methacrylate, nonylmethacrylate, decyl methacrylate, lauryl methacrylate, eicosylmethacrylate and the like and mixtures thereof. Suitable free-radicalpolymerizable olefinic acids include acrylic acid, methacrylic acid,fumaric acid, crotonic acid, itaconic acid, 2-acryloxypropionic acid,and the like and mixtures thereof.

Various amounts of other ethylenically-unsaturated monomers canoptionally be used provided that the polymeric additive has a softeningpoint greater than about 40° C. and a number average molecular weightless than about 35,000. Optional ethylenically-unsaturated monomerssuitable for use in the polymeric additive include, for example,styrene, alpha-methyl styrene, vinyl toluene, acrylonitrile,methacrylonitrile, ethylene, vinyl acetate, vinyl chloride, vinylidenechloride, acrylamide, methacrylamide 2-cyanoethyl acrylate, 2-cyanoethylmethacrylate, dimethylaminoethyl methacrylate, dimethylaminopropylmethacrylate t-butylaminoethyl methacrylate, glycidyl acrylate, glycidylmethacrylate, benzyl acrylate, benzyl methacrylate, phenyl acrylate,phenyl methacrylate and the like. The amount of the polymeric additiveused may be in the range of about 1% to about 55% by weight, based onthe total weight of the adhesive composition. Such low molecular weightadditives as described in U.S. Pat. No. 4,912,169, the disclosure ofwhich is hereby incorporated by reference.

In certain embodiments, the adhesives have a relatively high solidscontent. Typically, the weight percentage of solids is greater than 50%,or at least 60%, or at least 70%.

In certain embodiments, the present subject matter adhesives orcompositions are polymerized and/or crosslinked by exposure to actinicradiation, and particularly ultraviolet (UV) radiation or near UVradiation. Electron beam radiation can also be used. As will beappreciated, sufficient exposure to such radiation causes polymerizationand/or crosslinking involving various functional groups incorporated inthe polymers.

Use of the aspects described herein enable formulation of a pre-adhesiveformulation that can be further processed by subsequent or additionalexposure to actinic radiation and particularly UV radiation. Thus, aninitial batch or a desired amount of pre-adhesive can be polymerized orat least partially polymerized in bulk and then stored or held for laterapplication or coating to a substrate of interest.

After the adhesive is coated on a substrate at a desired coat weight,the coated substrate is irradiated with actinic radiation andparticularly UV radiation to yield a crosslinked adhesive and in manyembodiments a pressure sensitive adhesive having high cohesive strengthat room and elevated temperatures. A variety of UV light sources areknown, including low, high, and medium pressure mercury lamps, whichemit over a wide range of wavelengths. Most pigmented and unpigmentedadhesives can be readily cured using a medium pressure mercury lamp,which has emission bands ranging from about 240 to about 410 nanometers.Alternatively, UV sources that emit over a more narrow range ofwavelengths can be used if desired, so long as the emission spectrum ofthe source overlaps with the absorption spectrum of the initiator(s)employed within the adhesive. Where the adhesive is pigmented withtitanium dioxide or similar pigments, the preferred initiator hasabsorption bands in the near UV region, and a UV source that emits atleast in that region is employed.

FIG. 1 is a process schematic diagram depicting a representative processand system 10 for producing an adhesive and polymerizing andcrosslinking the adhesive in accordance with the present subject matter.The system 10 generally comprises a dispenser or heater 12 forintroducing one or more adhesives, polymers, and/or monomers via feedline 14 to a blender or mixer 22. Also provided are additional feedlines 16, 18, and 20 which can be selectively metering desired amountsof initiator, optional components and/or other monomers, and ancillarycomponents or other additives to the mixer 22. It will be appreciatedthat the initiator can be introduced in the form of polymerizablemonomers which are polymerized with or separately from monomer(s) thatform the adhesive.

After appropriate mixing of the adhesive, polymers and/or monomers,photoinitiators, and optional components, the resulting pre-adhesive isdirected through line 24 to a reactor 26 which can be in the form of atube reactor for example. The reactor 26 can be in a variety ofdifferent forms however typically defines an interior region forreceiving adhesive or pre-adhesive. The reactor 26 is configured toallow actinic radiation such as UV radiation to enter the interior ofthe reactor from one or more radiation sources as described herein. Theadhesive or pre-adhesive is directed through the reactor 26 and exposedto actinic radiation from UV emitters 28, 30 that emit UV light orradiation shown as rays 29, 31 for example, having a wavelengthcorresponding to an activation wavelength of the photoinitiator groupand/or the initiators. The flow rate, i.e., residence time of adhesiveor pre-adhesive in the reactor 26; intensity of the UV light; and otherfactors are adjusted to produce a partially or fully polymerizedadhesive exiting the reactor 26 via line 32. Polymerization betweenmonomer(s) primarily occurs in the reactor 26. It is contemplated thatthermal-based polymerization of monomers could be performed instead of,or in addition to, radiation-based polymerization.

The adhesive partially or fully polymerized in line 32 may be directlydeposited or applied to one or more substrates on a moving web 42(typically driven by rotating roller 40) via line 34, or directed vialine 36 to a storage unit 44 for additional processing and/or subsequentapplication.

Upon deposition of the adhesive shown in FIG. 1 as regions 46, theadhesive typically on the moving web 42, is irradiated by another UVemitter in a stage 50 that directs UV rays 51 upon the regions 46 tocrosslink the adhesive. Crosslinked adhesive 52 results.

Articles

The present subject matter provides a wide array of articles thatinclude the noted compositions, pre-adhesives, and/or adhesives.Examples of such articles include adhesive tapes including double sidedand single sided tapes; label stock; label constructions; packagingproducts and assemblies including food packages, packaging for householdgoods and industrial goods and particularly reclosable packages; andother items.

FIG. 2 illustrates a tape article 100 in accordance with an embodimentof the present subject matter. The tape article 100 is shown in a rollform, however, it will be appreciated that the tape could be in a flat,sheet, or Z-fold form. The tape article 100 generally includes asubstrate 110 defining a first face 112 and an oppositely directedsecond face 114. The tape 100 includes a layer or region of an adhesiveas described herein disposed on one or both faces 112, 114. One or morerelease liners and/or low surface energy coatings can be used asdescribed in greater detail herein.

FIG. 3 is a schematic cross sectional view of a tape 100A comprising asubstrate 110 defining a first face 112 and an oppositely directedsecond face 114. The tape 100A also comprises a layer or region of anadhesive 120 disposed on one of the faces such as for example face 114.One or more low surface energy coatings can be disposed on the face 112of the substrate 110.

FIG. 4 is a schematic cross sectional view of a tape 100B comprising asubstrate 110 defining a first face 112 and an oppositely directedsecond face 114. The tape 100B also comprises a layer or region of anadhesive 120 disposed on one of the faces such as for example face 114.The tape 100B also comprises a release liner 130 covering the adhesive120. One or more low surface energy coatings can be disposed on the face112 of the substrate 110.

FIG. 5 is a schematic cross sectional view of a tape 100C comprising asubstrate 110 defining a first face 112 and an oppositely directedsecond face 114. The tape 100C also comprises a first layer or region ofan adhesive 120 disposed on one of the faces such as for example face114. The tape 100C also comprises a second layer or region of anadhesive 125 disposed on the face 112 of the substrate 110.

FIG. 6 is a schematic cross sectional view of a tape 100D comprising asubstrate 110 defining a first face 112 and an oppositely directedsecond face 114. The tape 100D also comprises a first layer or region ofan adhesive 120 disposed on one of the faces such as for example face114. The tape 100D also comprises a second layer or region of anadhesive 125 on the face 112. The tape 100D also comprises a firstrelease liner 130 covering the adhesive 120. And, the tape 100Dadditionally comprises a second release liner 135 covering the adhesive125.

FIG. 7 is a schematic cross sectional view of a sealing, closure, orreclosure assembly 200 in accordance with the present subject matter.This assembly comprises a first substrate 210 defining a first substrateface 212, a second substrate 230 defining a second substrate face 214,and one or more layers or regions of an adhesive 220 defining anadhesive face 222. The adhesive 220 is disposed on one or both substratefaces 212, 214. The adhesive 220 serves to seal and/or adhere thesubstrates 210, 230 together upon contact between the adhesive face 222and the substrate face 212. As will be understood, the adhesive 220 isany of the adhesives described herein. The assembly 200 can be utilizedin association with and/or incorporated in a wide array of packagingproducts including for example food packages, packages for householdgoods, industrial goods packages, and in particular recloseablepackages.

The adhesive layer may have a thickness as desired for a particularpurpose or intended use. In one embodiment, the adhesive layer may havea thickness from about 10 to about 125, or from about 10 to about 75, orfrom about 10 to about 50 microns. In one embodiment, the coat weight ofthe adhesive may be in the range of about 10 to about 50 grams persquare meter (gsm), and in one embodiment about 20 to about 35 gsm.

Release liners for use in the present subject matter may be those knownin the art or those later discovered. In general, suitable releaseliners include, but are not limited to, polyethylene coated papers witha commercial silicone release coating, polyethylene coated polyethyleneterephthalate films with a commercial silicone release coating, or castpolypropylene films that can be embossed with a pattern or patternswhile making such films, and thereafter coated with a commercialsilicone release coating. An exemplary release liner is kraft paperwhich has a coating of low density polyethylene on the front side with asilicone release coating and a coating of high density polyethylene orpolypropylene on the back side. Other release liners known in the artare also suitable as long as they are selected for their releasecharacteristics relative to the pressure sensitive adhesive chosen foruse in the adhesive article, that is, the adhesive will have a greateraffinity for the face stock than the liner.

As previously noted, one or more low surface energy coatings can be usedin the articles utilizing the adhesives described herein. For example,for rolled tape products it may be desirable to provide a coating of alow surface energy agent along a rear face of a substrate or tapecomponent that contacts the adhesive. Nonlimiting examples of lowsurface energy coatings include silicone agents, polypropylene or otherpolyolefins, certain fluorocarbons, and certain fatty acid esters.

A benefit of particular adhesives of the present subject matter involvesmaintenance of performance criteria upon continued exposure to UVradiation. For example, a disadvantage of many conventional UV cured,randomly crosslinked adhesive networks is that additional UV exposureresults in additional crosslinking. This may in turn result inundesirable changes in the adhesive and/or its performance.Specifically, this may be undesirable for clear or transparent labelsthat are UV printed downstream. In contrast, many embodiments of thepresent subject matter adhesives do not exhibit performance changes uponadditional UV exposure.

Examples

The following test methods were used for evaluating the adhesiveproperties of various acrylic adhesives.

TABLE 2 PSA Performance Test Methods Test Condition 90° Peel a, b, c, d20 minute dwell 24 hour dwell  1 week dwell  1 month % Insoluble Polymere Melt Flow f

-   -   (a) Peel, sample applied to a polyethylene terephthalate (PET)        panel with a 5 pound roller with 5 passes in each direction.        Samples conditioned and tested at 23° C.    -   (b) Peel, sample applied to a polyethylene terephthalate (PET)        film applied to a rigid PVC panel with double sided tape with a        5 pound roller with 5 passes in each direction. Samples        conditioned and tested at 23° C.    -   (c) Peel, sample applied to a high density polyethylene with a 5        pound roller with 5 passes in each direction. Samples        conditioned and tested at 23° C.    -   (d) Peel, sample applied to a high density polypropylene with a        5 pound roller with 5 passes in each direction. Samples        conditioned and tested at 23° C.    -   (e) % Insoluble polymer: 0.05-0.10 grams of cured polymer is        sealed in a 5 micrometer porous PFTE membrane filter and tumbled        in tetrahydrofuran (THF) for 1 week. The weight of polymer        before soak and after soak is measured to achieve a % of polymer        that was insoluble in the THF.    -   (f) Melt flow was measured with an AR2000 Rheometer fitted with        a stainless steel 2° cone and plate. Examples were evaluated at        0.25 sec⁻¹ and a gap of 100 micrometer. Temperature was ramped        at 0.5° C. per minute after a ten minute equilibration time at        the starting temperature.

The present subject matter is further described by reference to thefollowing non-limiting examples.

Example 1: Preparation of Segmented Acrylic Polymer Having BenzophenoneFunctionality Using SFRP Agent (KH9-76-2 Per Chain)

An acrylic copolymer with reactive functionalities positioned in thesegment adjacent to the polymer chain end is prepared as follows. Into a1500 ml reactor equipped with a heating jacket, agitator, refluxcondenser, feed tanks and nitrogen gas inlet there is charged 4.36 g ofBlocBuilder MA (SFRP Agent). The reactor is then inerted with nitrogenfor 1 hour at 0.5 litre/min. Monomers and solvents are added in thefollowing amounts to a feed vessel and inerted with nitrogen for 1 hourat 0.5 litre/min. After inertion, the monomer and solvent mix was addedto the reactor to generate the segment adjacent to the polymer chainends.

-   -   55.92 g Butyl Acrylate    -   55.92 g 2-Ethyl Hexyl Acrylate    -   1.13 g Acrylic Acid    -   6.00 g 4-Methacrylic Benzophenone    -   110.50 g Propyl Acetate

The reactor charge is heated to reflux conditions (reactor jacket 125°C.) with a constant nitrogen purge. At 100° C., a 60 minute hold isstarted in which the reaction will reach a reflux during this hold atapproximately 112° C. This is to create the UV functional segment with atheoretical Mn of 10,408 g/mol. During the 60 minute hold, a reagentfeed mixture with an active nitrogen purge of 181.47 g propyl acetate,503.31 g butyl acrylate, 503.31 g 2-ethylhexyl acrylate and 10.17 gacrylic acid is weighed into a feed vessel and inerted with nitrogen at0.5 litre/minute. After the initial 60 minute hold, the reagent feed isadded over a period of sixty minutes to the reactor at a rate of 2grams/minute. After the sixty minute feed, the rate is ramped to 5.99grams/min until the mixture is depleted. During the reagent feeds thetemperature of the reaction is held at 118-122° C. The reactionconditions are maintained after completion of the reagent feed until aconversion of at least 97% of butyl acrylate and 2-ethylhexyl acrylateis achieved. This is to create the remainder of the non-UV functionalsegment adjacent to the UV functional segment at the end of the polymer.The total theoretical Mn of the non-UV functional segment is 89,591g/mol. At this time, the polymer is cooled to 85° C. Once the polymer isbelow 90° C., 11.43 g of butyl acrylate is added to the reactor andallowed to mix for 15 minutes. Once the polymer is 85° C., 5.67 g oftertiary amyl peroxy pivalate and 50.80 g propyl acetate are mixed in a100 mL feed vessel and inerted for 15 minutes with nitrogen at 0.5litre/minute. After inertion, the pivalate solution is added to thereactor over ninety minutes. At the completion of the pivalate feed, thereaction temperature is held between 85° C. and 90° C. for 2 hours. Atthe end of the 2 hour hold, 34.50 g of Foral 85LB pre-dissolved in 14.78g ethyl acetate is added to the polymer. The resulting solution polymeris then cooled to ambient temperature and discharged from the reactor.

Example 2: Preparation of Segmented Acrylic Polymer Having BenzophenoneFunctionality Using SFRP Agent (KH9-68-4 Per Chain)

An acrylic copolymer with reactive functionalities positioned in thesegment adjacent to the polymer chain end is prepared as follows. Into a1500 ml reactor equipped with a heating jacket, agitator, refluxcondenser, feed tanks and nitrogen gas inlet there is charged 4.34 g ofBlocBuilder MA (SFRP Agent). The reactor is then inerted with nitrogenfor 1 hour at 0.5 litre/min. Monomers and solvents are added in thefollowing amounts to a feed vessel and inerted with nitrogen for 1 hourat 0.5 litre/min. After inertion, the monomer and solvent mix was addedto the reactor to generate the segment adjacent to the polymer chainends.

-   -   55.70 g Butyl Acrylate    -   55.70 g 2-Ethyl Hexyl Acrylate    -   1.13 g Acrylic Acid    -   11.95 g 4-Methacrylic Benzophenone    -   110.06 g Propyl Acetate

The reactor charge is heated to reflux conditions (reactor jacket 125°C.) with a constant nitrogen purge. At 100° C., a 60 minute hold isstarted in which the reaction will reach a reflux during this hold atapproximately 112° C. This is to create the UV functional segment with atheoretical Mn of 10,933 g/mol. During the 60 minute hold, a reagentfeed mixture with an active nitrogen purge of 180.74 g propyl acetate,501.29 g butyl acrylate, 501.29 g 2-ethylhexyl acrylate and 10.13 gacrylic acid is weighed into a feed vessel and inerted with nitrogen at0.5 litre/minute. After the initial 60 minute hold, the reagent feed isadded over a period of sixty minutes to the reactor at a rate of 2grams/minute. After the sixty minute feed, the rate is ramped to 5.96grams/min until the mixture is depleted. During the reagent feeds thetemperature of the reaction is held at 118-122° C. The reactionconditions are maintained after completion of the reagent feed until aconversion of at least 97% of butyl acrylate and 2-ethylhexyl acrylateis achieved. This is to create the remainder of the non-UV functionalsegment adjacent to the UV functional segment at the end of the polymer.The total theoretical Mn of the non-UV functional segment is 89,066g/mol. At this time, the polymer is cooled to 85° C. Once the polymer isbelow 90° C., 11.39 g of butyl acrylate is added to the reactor andallowed to mix for 15 minutes. Once the polymer is 85° C., 5.68 g oftertiary amyl peroxy pivalate and 50.60 g propyl acetate are mixed in a100 mL feed vessel and inerted for 15 minutes with nitrogen at 0.5litre/minute. After inertion, the pivalate solution is added to thereactor over ninety minutes. At the completion of the pivalate feed, thereaction temperature is held between 85° C. and 90° C. for 2 hours. Atthe end of the 2 hour hold, 35.54 g of Foral 85LB pre-dissolved in 15.23g ethyl acetate is added to the polymer. The resulting solution polymeris then cooled to ambient temperature and discharged from the reactor.

Example 3: Preparation of Segmented Acrylic Polymer Having BenzophenoneFunctionality Using SFRP Agent (KH9-75-2.6 Per Chain)

An acrylic copolymer with reactive functionalities positioned in thesegment adjacent to the polymer chain end is prepared as follows. Into a1500 ml reactor equipped with a heating jacket, agitator, refluxcondenser, feed tanks and nitrogen gas inlet there is charged 4.35 g ofBlocBuilder MA (SFRP Agent). The reactor is then inerted with nitrogenfor 1 hour at 0.5 litre/min. Monomers and solvents are added in thefollowing amounts to a feed vessel and inerted with nitrogen for 1 hourat 0.5 litre/min. After inertion, the monomer and solvent mix was addedto the reactor to generate the segment adjacent to the polymer chainends.

-   -   55.85 g Butyl Acrylate    -   55.85 g 2-Ethyl Hexyl Acrylate    -   1.13 g Acrylic Acid    -   7.99 g 4-Methacrylic Benzophenone    -   110.35 g Propyl Acetate

The reactor charge is heated to reflux conditions (reactor jacket 125°C.) with a constant nitrogen purge. At 100° C., a 60 minute hold isstarted in which the reaction will reach a reflux during this hold atapproximately 112° C. This is to create the UV functional segment with atheoretical Mn of 10,408 g/mol. During the 60 minute hold, a reagentfeed mixture with an active nitrogen purge of 181.23 g propyl acetate,502.64 g butyl acrylate, 502.64 g 2-ethylhexyl acrylate and 10.15 gacrylic acid is weighed into a feed vessel and inerted with nitrogen at0.5 litre/minute. After the initial 60 minute hold, the reagent feed isadded over a period of sixty minutes to the reactor at a rate of 2grams/minute. After the sixty minute feed, the rate is ramped to 5.98grams/min until the mixture is depleted. During the reagent feeds thetemperature of the reaction is held at 118-122° C. The reactionconditions are maintained after completion of the reagent feed until aconversion of at least 97% of butyl acrylate and 2-ethylhexyl acrylateis achieved. This is to create the remainder of the non-UV functionalsegment adjacent to the UV functional segment at the end of the polymer.The total theoretical Mn of the non-UV functional segment is 89,591g/mol. At this time, the polymer is cooled to 85° C. Once the polymer isbelow 90° C., 11.42 g of butyl acrylate is added to the reactor andallowed to mix for 15 minutes. Once the polymer is 85° C., 5.68 g oftertiary amyl peroxy pivalate and 50.74 g propyl acetate are mixed in a100 mL feed vessel and inerted for 15 minutes with nitrogen at 0.5litre/minute. After inertion, the pivalate solution is added to thereactor over ninety minutes. At the completion of the pivalate feed, thereaction temperature is held between 85° C. and 90° C. for 2 hours. Theresulting solution polymer is then cooled to ambient temperature anddischarged from the reactor.

Example 4: Preparation of Segmented Acrylic Polymer Having BenzophenoneFunctionality Using SFRP Agent (KH9-21-1.3 Per Chain)

An acrylic copolymer with reactive functionalities positioned in thesegment adjacent to the polymer chain end is prepared as follows. Into a1500 ml reactor equipped with a heating jacket, agitator, refluxcondenser, feed tanks and nitrogen gas inlet there is charged 3.63 g ofBlocBuilder MA (SFRP Agent). The reactor is then inerted with nitrogenfor 1 hour at 0.5 litre/min. Monomers and solvents are added in thefollowing amounts to a feed vessel and inerted with nitrogen for 1 hourat 0.5 litre/min. After inertion, the monomer and solvent mix was addedto the reactor to generate the segment adjacent to the polymer chainends.

-   -   46.67 g Butyl Acrylate    -   46.67 g 2-Ethyl Hexyl Acrylate    -   0.94 g Acrylic Acid    -   3.34 g 4-Methacrylic Benzophenone    -   92.21 g Propyl Acetate

The reactor charge is heated to reflux conditions (reactor jacket 125°C.) with a constant nitrogen purge. At 100° C., a 60 minute hold isstarted in which the reaction will reach a reflux during this hold atapproximately 112° C. This is to create the UV functional segment with atheoretical Mn of 10,408 g/mol. During the 60 minute hold, a reagentfeed mixture with an active nitrogen purge of 151.43 g propyl acetate,419.99 g butyl acrylate, 419.99 g 2-ethylhexyl acrylate and 8.48 gacrylic acid is weighed into a feed vessel and inerted with nitrogen at0.5 litre/minute. After the initial 60 minute hold, the reagent feed isadded over a period of sixty minutes to the reactor at a rate of 2grams/minute. After the sixty minute feed, the rate is ramped to 4.89grams/min until the mixture is depleted. During the reagent feeds thetemperature of the reaction is held at 118-122° C. The reactionconditions are maintained after completion of the reagent feed until aconversion of at least 97% of butyl acrylate and 2-ethylhexyl acrylateis achieved. This is to create the remainder of the non-UV functionalsegment adjacent to the UV functional segment at the end of the polymer.The total theoretical Mn of the non-UV functional segment is 89,591g/mol. At this time, the polymer is cooled to 85° C. Once the polymer isbelow 90° C., 9.54 g of butyl acrylate is added to the reactor andallowed to mix for 15 minutes. Once the polymer is 85° C., 4.73 g oftertiary amyl peroxy pivalate and 42.39 g propyl acetate are mixed in a100 mL feed vessel and inerted for 15 minutes with nitrogen at 0.5litre/minute. After inertion, the pivalate solution is added to thereactor over ninety minutes. At the completion of the pivalate feed, thereaction temperature is held between 85° C. and 90° C. for 2 hours. Theresulting solution polymer is then cooled to ambient temperature anddischarged from the reactor.

Example 5: Preparation of Segmented Acrylic Polymer Having BenzophenoneFunctionality Using SFRP Agent (KH9-77-1.65 Per Chain))

An acrylic copolymer with reactive functionalities positioned in thesegment adjacent to the polymer chain end is prepared as follows. Into a1500 ml reactor equipped with a heating jacket, agitator, refluxcondenser, feed tanks and nitrogen gas inlet there is charged 4.36 g ofBlocBuilder MA (SFRP Agent). The reactor is then inerted with nitrogenfor 1 hour at 0.5 litre/min. Monomers and solvents are added in thefollowing amounts to a feed vessel and inerted with nitrogen for 1 hourat 0.5 litre/min. After inertion, the monomer and solvent mix was addedto the reactor to generate the segment adjacent to the polymer chainends.

-   -   55.96 g Butyl Acrylate    -   55.96 g 2-Ethyl Hexyl Acrylate    -   1.13 g Acrylic Acid    -   5.00 g 4-Methacrylic Benzophenone    -   110.57 g Propyl Acetate

The reactor charge is heated to reflux conditions (reactor jacket 125°C.) with a constant nitrogen purge. At 100° C., a 60 minute hold isstarted in which the reaction will reach a reflux during this hold atapproximately 112° C. This is to create the UV functional segment with atheoretical Mn of 10,408 g/mol. During the 60 minute hold, a reagentfeed mixture with an active nitrogen purge of 181.59 g propyl acetate,503.65 g butyl acrylate, 503.65 g 2-ethylhexyl acrylate and 10.17 gacrylic acid is weighed into a feed vessel and inerted with nitrogen at0.5 litre/minute. After the initial 60 minute hold, the reagent feed isadded over a period of sixty minutes to the reactor at a rate of 2grams/minute. After the sixty minute feed, the rate is ramped to 5.99grams/min until the mixture is depleted. During the reagent feeds thetemperature of the reaction is held at 118-122° C. The reactionconditions are maintained after completion of the reagent feed until aconversion of at least 97% of butyl acrylate and 2-ethylhexyl acrylateis achieved. This is to create the remainder of the non-UV functionalsegment adjacent to the UV functional segment at the end of the polymer.The total theoretical Mn of the non-UV functional segment is 89,591g/mol. At this time, the polymer is cooled to 85° C. Once the polymer isbelow 90° C., 11.44 g of butyl acrylate is added to the reactor andallowed to mix for 15 minutes. Once the polymer is 85° C., 5.67 g oftertiary amyl peroxy pivalate and 50.84 g propyl acetate are mixed in a100 mL feed vessel and inerted for 15 minutes with nitrogen at 0.5litre/minute. After inertion, the pivalate solution is added to thereactor over ninety minutes. At the completion of the pivalate feed, thereaction temperature is held between 85° C. and 90° C. for 2 hours. Atthe end of the 2 hour hold, 32.52 g of Foral 85LB pre-dissolved in 13.94g ethyl acetate is added to the polymer. The resulting solution polymeris then cooled to ambient temperature and discharged from the reactor.

Example 6: Preparation of Segmented Acrylic Polymer Having BenzophenoneFunctionality Using SFRP Agent (KH9-81-2.3 Per Chain)

An acrylic copolymer with reactive functionalities positioned in thesegment adjacent to the polymer chain end is prepared as follows. Into a1500 ml equipped with a heating jacket, agitator, reflux condenser, feedtanks and nitrogen gas inlet there is charged 4.35 g of BlocBuilder MA(SFRP Agent). The reactor is then inerted with nitrogen for 1 hour at0.5 litre/min. Monomers and solvents are added in the following amountsto a feed vessel and inerted with nitrogen for 1 hour at 0.5 litre/min.After inertion, the monomer and solvent mix was added to the reactor togenerate the segment adjacent to the polymer chain ends.

-   -   55.89 g Butyl Acrylate    -   55.89 g 2-Ethyl Hexyl Acrylate    -   1.13 g Acrylic Acid    -   7.00 g 4-Methacrylic Benzophenone    -   110.43 g Propyl Acetate

The reactor charge is heated to reflux conditions (reactor jacket 125°C.) with a constant nitrogen purge. At 100° C., a 60 minute hold isstarted in which the reaction will reach a reflux during this hold atapproximately 112° C. This is to create the UV functional segment with atheoretical Mn of 10,408 g/mol. During the 60 minute hold, a reagentfeed mixture with an active nitrogen purge of 181.35 g propyl acetate,502.97 g butyl acrylate, 502.97 g 2-ethylhexyl acrylate and 10.16 gacrylic acid is weighed into a feed vessel and inerted with nitrogen at0.5 litre/minute. After the initial 60 minute hold, the reagent feed isadded over a period of sixty minutes to the reactor at a rate of 2grams/minute. After the sixty minute feed, the rate is ramped to 5.99grams/min until the mixture is depleted. During the reagent feeds thetemperature of the reaction is held at 118-122° C. The reactionconditions are maintained after completion of the reagent feed until aconversion of at least 97% of butyl acrylate and 2-ethylhexyl acrylateis achieved. This is to create the remainder of the non-UV functionalsegment adjacent to the UV functional segment at the end of the polymer.The total theoretical Mn of the non-UV functional segment is 89,591g/mol. At this time, the polymer is cooled to 85° C. Once the polymer isbelow 90° C., 11.42 g of butyl acrylate is added to the reactor andallowed to mix for 15 minutes. Once the polymer is 85° C., 5.67 g oftertiary amyl peroxy pivalate and 50.77 g propyl acetate are mixed in a100 mL feed vessel and inerted for 15 minutes with nitrogen at 0.5litre/minute. After inertion, the pivalate solution is added to thereactor over ninety minutes. At the completion of the pivalate feed, thereaction temperature is held between 85° C. and 90° C. for 2 hours. Atthe end of the 2 hour hold, 35.61 g of Foral 85LB pre-dissolved in 15.26g ethyl acetate is added to the polymer. The resulting solution polymeris then cooled to ambient temperature and discharged from the reactor.

Example 7: Formulation of Example 3 (AK9-97)

Three percent Foral 85LB was added to the polymer of Example 3 based onsolid content to result in a 97:3 ratio polymer to tackifier.

Example 8: Formulation of Example 4 (AK9-65)

Three percent Foral 85LB was added to the polymer of Example 4 based onsolid content to result in a 97:3 ratio polymer to tackifier.

Example 9: Comparative Example from Commercial Supplier

This adhesive is a formulated high molecular weight solvent acrylicpolymer.

Example 10: Comparative Example from Commercial Supplier

This adhesive is a formulated high molecular weight solvent acrylicpolymer.

Table 3 summarizes Examples 1-10.

TABLE 3 Summary of Examples 1-10 Example 1 2 3 4 5 6 7 8 9 10 Lot 76 6875 21 77 81 AK9-97 AK9-65 Commercial Commercial #bp/ch 2 4 2.6 1.3 1.652.3 97% 97% Control Control Solids 76.92% 77.01% 77.18% 77.12% 76.92%77.09% Ex. 3 Ex. 4   39%   26% BA 49.74% 49.49% 49.66% 49.83% 49.79%49.70% — — EHA 48.75% 48.49% 48.66% 48.83% 48.79% 48.71% AA 0.99% 0.98%0.98% 0.99% 0.99% 0.98% 4MABP 0.52% 1.04% 0.70% 0.35% 0.44% 0.61% Total100.00% 100.00% 100.00% 100.00% 100.00% 100.00% Parts 2.89% 2.89% 0.00%0.00% 2.73% 3.19% 3.00% 3.00% 0.00% 0.00% Foral Mn 55223 59709 See See52849 55130 56388 44202 112718 302632 (g/mol) Ex. 7 Ex. 8 Mw 186276194747 169349 182701 197077 191279 463059 929513 (g/mol) PDI 3.37 3.263.20 3.31 3.50 4.33 4.11 3.07

Test Results

The adhesives of Examples 1, 2, 5, 6, 7, and 8 were coated onto 2-milpolyethylene terephthalate with a 100% solids platinum cured siliconerelease layer at 10-12 grams per square meter (gsm) and dried at ambienttemperature for 15 minutes followed by 50° C. for 15 minutes to isolatethe formulation from solvent. After drying, the coating was cured withUV radiation at various energy densities to achieve various cure levels.The cured coating was then laminated to a 2 mil BOPP film and dwelled ina 50° C. oven for 24 hours followed by a 24 hour dwell in a climatecontrolled room at 75° F. and 50% humidity before testing.

The Comparative Examples 9 and 10 were obtained from Avery Dennison.

FIGS. 10 and 11 present results of evaluations of samples from variousexamples.

Tables 4-7 present results of evaluations and compare 90° peel adhesiontrials of samples from Examples 1, 9, and 10.

TABLE 4 Comparing Examples 1, 9, and 10 90° Peel adhesion Coatweight toRigid PET panel (pli) (gsm) 20 min 24 hr 1 week 1 month Example 1 cured@ 12.5 1.32 1.36 1.43 1.45 5 mJ/cm² UV-C Example 1 cured @ 10.0 0.930.90 0.96 1.02 9 mJ/cm² UV-C Comparative 17.5 1.17 1.23 1.32 1.28Example 9 Comparative 17.5 1.16 1.23 1.30 1.29 Example 10

TABLE 5 Comparing Examples 1, 9, and 10 90° Peel adhesion to CoatweightFlexible PET film (pli) (gsm) 20 min 24 hr 1 week 1 month Example 1cured @ 12.5 0.98 n/a 1.14 n/a 5 mJ/cm2 UV-C Example 1 cured @ 10.0 0.63n/a 0.81 n/a 9 mJ/cm2 UV-C Comparative 17.5 0.88 n/a 0.98 n/a Example 9Comparative 17.5 0.74 n/a 0.99 n/a Example 10

TABLE 6 Comparing Examples 1, 9, and 10 90° Peel adhesion to CoatweightRigid PP panel (pli) (gsm) 20 min 24 hr 1 week 1 month Example 1 cured @12.5 0.79 0.80 0.84 0.80 5 mJ/cm² UV-C Example 1 cured @ 10.0 0.60 0.590.63 0.67 9 mJ/cm² UV-C Comparative 17.5 0.71 0.74 0.78 0.67 Example 9Comparative 17.5 0.60 0.61 0.63 0.64 Example 10

TABLE 7 Comparing Examples 1, 9, and 10 90° Peel adhesion to CoatweightRigid HDPE panel (pli) (gsm) 20 min 24 hr 1 week 1 month Example 1 cured@ 12.5 0.53 0.55 0.59 0.55 5 mJ/cm² UV-C Example 1 cured @ 10.0 0.340.36 0.40 0.42 9 mJ/cm² UV-C Comparative 17.5 0.30 0.34 0.35 0.41Example 9 Comparative 17.5 0.21 0.25 0.23 0.29 Example 10

FIGS. 12 and 13 present results of melt flow evaluations of samples ofExamples 1 and 6.

Example #11: Preparation of Segmented Acrylic Polymer HavingBenzophenone Functionality Using SFRP Agent (KH8-15-PseudoTelechelic->2.5 Per Chain End)

An acrylic copolymer with reactive functionalities positioned in thesegment adjacent to the polymer chain ends is prepared as follows. Intoa 1500 ml reactor equipped with a heating jacket, agitator, refluxcondenser, feed tanks and nitrogen gas inlet there is charged 2.89 g ofBlocBuilder MA (SFRP Agent). The reactor is then inerted with nitrogenfor 1 hour at 0.5 litre/min. Monomers and solvents are added in thefollowing amounts to a feed vessel and inerted with nitrogen for 1 hourat 0.5 litre/min. After inertion, the monomer and solvent mix was addedto the reactor to generate the segment adjacent to the polymer chainends.

-   -   74.62 g Butyl Acrylate    -   6.65 g 4-Methacrylic Benzophenone    -   73.42 g Propyl Acetate

The reactor charge is heated to reflux conditions (reactor jacket 125°C.) with a constant nitrogen purge. At 100° C., a 60 minute hold isstarted in which the reaction will reach a reflux during this hold atapproximately 112° C. This is to create the UV functional segment with atheoretical Mn of 10,700 g/mol. During the 60 minute hold, a reagentfeed mixture with an active nitrogen purge of 84.39 g propyl acetate and671.62 g butyl acrylate is weighed into a feed vessel and inerted withnitrogen at 0.5 litre/minute. After the initial 60 minute hold, thereagent feed is added over a period of sixty minutes to the reactor at arate of 2 grams/minute. After the sixty minute feed, the rate is rampedto 4.41 grams/min until the mixture is oxygen depleted. During thereagent feeds the temperature of the reaction is held at 118-122° C. Thereaction conditions are maintained after completion of the reagent feeduntil a conversion of at least 90% of butyl acrylate is achieved.Conversion for this example was 92.3%. This is to create the remainderof the non-UV functional segment adjacent to the UV functional segmentat the end of the polymer. The total theoretical Mn of the non-UVfunctional segment is 88,425 g/mol. Prior to the 92.3% BA conversion,6.65 g of 4-Methacrylic Benzophenone, 74.62 g of Butyl Acrylate, and42.00 g of Propyl Acetate are weighed into a feed vessel and inertedwith nitrogen at 0.5 litre/min until the mixture is oxygen depleted.After sparging, the reagent feed is added to the reactor at the 92.3% BAconversion at the max feed rate of ˜g/min. The reaction is held at118-122° C. until the BA conversion is >95%. At this time, the polymeris cooled to 85° C. Once the polymer is 85° C., 3.80 g of tertiary amylperoxy pivalate and 33.76 g propyl acetate are mixed in a 100 mL feedvessel and inerted for 15 minutes with nitrogen at 0.5 litre/minute.After inertion, the pivalate solution is added to the reactor overninety minutes. At the completion of the pivalate feed, the reactiontemperature is held between 85° C. and 90° C. for 2 hours. The resultingsolution polymer is then cooled to ambient temperature and dischargedfrom the reactor. The theoretical molecular weight was 109,825 g/mol Mnand the actual measured to be 42,601 g/mol Mn, 206,800 g/mol Mw, and4.85 PDI.

TABLE 7 Testing Results for Example #11 90° Peel adhesion to CoatweightFlexible PET film (pli) (gsm) 20 min 24 hr 1 week 1 month Example #11cured 12.2 0.64 0.71 n/a n/a @ 12 mJ/cm² UV-C Example #11 cured 12.20.41 0.42 n/a n/a @ 24 mJ/cm² UV-C Example #11 cured 12.2 0.29 0.29 n/an/a @ 36 mJ/cm² UV-C

Many other benefits will not doubt become apparent from futureapplication and development of this technology.

Further examples consistent with the present teachings are set out inthe following number clauses.

Clause 1. An acrylic polymer comprising:

-   -   at least one acrylic block copolymer including    -   a first reactive segment of controlled molecular weight and        position that includes at least one monomer having a functional        group selected from the group consisting of a UV active        functional group, a reactive functional group, a non-reactive        functional group, and combinations thereof; and    -   a second segment of controlled molecular weight and position        that includes at least one monomer having a functional group        selected from the group consisting of a reactive functional        group, a non-reactive functional group, and combinations        thereof.

Clause 2. The acrylic polymer of Clause 1 wherein the first reactivesegment includes at least one monomer having a UV active functionalgroup, at least one monomer having a reactive functional group, and atleast one monomer having a non-reactive functional group.

Clause 3. The acrylic polymer of Clause 1 or 2 wherein the firstreactive segment includes at least one monomer having a UV activefunctional group and at least one monomer having a non-reactivefunctional group.

Clause 4. The acrylic polymer of any one of Clauses 1 to 3 wherein thesecond segment includes at least one monomer having a reactivefunctional group and at least one monomer having a non-reactivefunctional group.

Clause 5. The acrylic polymer of any one of Clauses 1 to 4 wherein thesecond segment includes at least one monomer having a non-reactivefunctional group.

Clause 6. The acrylic polymer of any one of Clauses 1 to 5 wherein thefirst reactive segment includes at least one monomer having anon-reactive functional group and at least one polymerizable comonomerhaving a crosslinkable functionality, the crosslinkable functionalityselected from the group consisting of a UV active functional group, areactive functional group, and combinations thereof.

Clause 7. The acrylic polymer of any one of Clauses 1 to 6 wherein thefirst reactive segment includes at least one monomer having anon-reactive functional group and at least one polymerizable comonomerhaving a crosslinkable functionality, the crosslinkable functionality isa UV active functional group.

Clause 8. The acrylic polymer of any one of Clauses 1 to 7 wherein theat least one monomer having a non-reactive functional group within thefirst reactive segment is the same type of monomer having a non-reactivefunctional group present in the second reactive segment.

Clause 9. The acrylic polymer of any one of Clauses 1 to 8 wherein theat least one monomer having a reactive functional group within the firstreactive segment is the same type of monomer having a reactivefunctional group present in the second reactive segment.

Clause 10. The acrylic polymer of any one of Clauses 1 to 9 wherein theat least one monomer having a reactive functional group includes atleast one monomer derived from the formula (II):

-   -   where R is H or CH₃ and X includes a functional group capable of        crosslinking,

wherein the functional group includes at least one functional groupselected from the group consisting of hydroxyl, carboxyl, carbonyl,carbonate ester, isocyanate, epoxy, vinyl, amine, amide, imide,anhydride, mercapto (thiol), acid, acrylamide, acetoacetyl groups,alkoxymethylol, cyclic ether groups, and combinations thereof.

Clause 11. The acrylic polymer of any one of Clauses 1 to 10 wherein theat least one monomer having a reactive functional group includes atleast one functionalized monomer derived from the formula (I):

-   -   where R₃ is H or CH₃ and R₄ is a branched or unbranched,        saturated alkyl group having 4 to 14 carbon atoms.

Clause 12. The acrylic polymer of any one of Clauses 1 to 11 wherein theat least one functionalized monomer includes a crosslinkable functionalgroup selected from the group consisting of hydroxyl, carboxyl,carbonyl, carbonate ester, isocyanate, epoxy, vinyl, amine, amide,imide, anhydride, mercapto (thiol), acid, acrylamide, acetoacetylgroups, alkoxymethylol, cyclic ether groups, and combinations thereof.

Clause 13. The acrylic polymer of any one of Clauses 1 to 12 wherein theat least one monomer having a non-reactive functional group includes atleast one monomer derived from the formula (I):

-   -   where R₃ is H or CH₃ and R₄ is a branched or unbranched,        saturated alkyl group having 4 to 14 carbon atoms.

Clause 14. The acrylic polymer of any one of Clauses 1 to 13 wherein theat least one monomer having a non-reactive functional group is derivedfrom C₁ to about C₂₀ alkyl, aryl, or cyclic acrylates or C₁ to about C₂₀alkyl, aryl, or cyclic methacrylates.

Clause 15. The acrylic polymer of any one of Clauses 1 to 14 wherein thefirst reactive segment includes about 40% to about 99% by weight of theat least one monomer having a non-reactive functional group.

Clause 16. The acrylic polymer of any one of Clauses 1 to 15 wherein theat least one monomer having a UV active functional group is about 10% orless by weight of the total polymer weight.

Clause 17. The acrylic polymer of any one of Clauses 1 to 16 wherein thesecond segment is non-reactive with the UV active functional groupand/or the reactive functional group.

Clause 18. The acrylic polymer of any one of Clauses 1 to 17 wherein theat least one monomer having a non-reactive functional group isnon-reactive with the UV active functional group and/or the reactivefunctional group.

Clause 19. The acrylic polymer of any one of Clauses 1 to 18 wherein thefirst reactive segment and the second segment are positioned adjacent tothe polymer chain ends.

Clause 20. The acrylic polymer of any one of Clauses 1 to 19 wherein thereactive functional groups and/or the non-reactive functional groups arerandomly spaced apart along the length of the polymer chain.

Clause 21. The acrylic polymer of any one of Clauses 1 to 20 wherein thefirst reactive segment comprises 40% or less of the total polymermolecular weight.

Clause 22. The acrylic polymer of any one of Clauses 1 to 21 wherein thefirst reactive segment and the second segment are molecularly misciblebefore cure.

Clause 23. The acrylic polymer of any one of Clauses 1 to 22 wherein theacrylic polymer is a single phase polymer at room temperature.

Clause 24. The acrylic polymer of any one of Clauses 1 to 23 wherein theacrylic polymer is a single phase polymer prior to crosslinking.

Clause 25. The acrylic polymer of any one of Clauses 1 to 24 wherein thefirst reactive segment and the second segment are molecularly misciblebefore cure as expressed by their properties in the bulk state that areindicative of a single phase polymer.

Clause 26. The acrylic polymer of any one of Clauses 1 to 25 wherein theacrylic polymer is a single phase liquid polymer at room temperature.

Clause 27. The acrylic polymer of any one of Clauses 1 to 26 wherein theacrylic polymer is a single phase liquid polymer prior to crosslinking.

Clause 28. The acrylic polymer of any one of Clauses 1 to 27 wherein theacrylic polymer is a liquid polymer at room temperature.

Clause 29. The acrylic polymer of any one of Clauses 1 to 28 wherein theacrylic polymer is a liquid polymer prior to crosslinking.

Clause 30. The acrylic polymer of any one of Clauses 1 to 29 wherein theacrylic polymer is a homogeneous polymer at room temperature.

Clause 31. The acrylic polymer of any one of Clauses 1 to 30 wherein theacrylic polymer is a homogeneous polymer prior to crosslinking.

Clause 32. The acrylic polymer of any one of Clauses 1 to 31 wherein theacrylic polymer is a homogeneous liquid polymer prior to crosslinking.

Clause 33. The acrylic polymer of any one of Clauses 1 to 32 wherein theacrylic polymer is a homogeneous liquid polymer at room temperature.

Clause 34. The acrylic polymer of any one of Clauses 1 to 33 wherein theacrylic polymer exhibits no heterogeneity prior to crosslinking.

Clause 35. The acrylic polymer of any one of Clauses 1 to 34 wherein theacrylic polymer exhibits no heterogeneity at room temperature.

Clause 36. The acrylic polymer of any one of Clauses 1 to 35 wherein theglass transition temperature (Tg) of the acrylic polymer is within arange of from about 15° C. to about −115° C.

Clause 37. The acrylic polymer of any one of Clauses 1 to 36 wherein theUV active functional group is selected from the group consisting ofbenzophenones, double bonds, and combinations thereof.

Clause 38. The acrylic polymer of any one of Clauses 1 to 37 wherein theUV active functional group is a benzophenone.

Clause 39. The acrylic polymer of any one of Clauses 1 to 38 wherein theUV active functional group is represented by Formula (III) as follows:

-   -   in which R₁ and R₂ is each independently an organic radical        selected from the group consisting of methyl, aryl, and alkyl.

Clause 40. The acrylic polymer of any one of Clauses 1 to 39 wherein R₁and R₂ is each independently an aromatic or substituted aromatic group.

Clause 41. The acrylic polymer of any one of Clauses 1 to 40 wherein R₁and R₂ is each independently a phenyl or substituted phenyl group.

Clause 42. The acrylic polymer of any one of Clauses 1 to 41 wherein theUV active functional group is selected from the group consisting ofacetophenone, an acetophenone derivative, benzophenone, a benzophenonederivative, anthraquinone, an anthraquinone derivative, benzile, abenzile derivative, thioxanthone, a thioxanthone derivative, xanthone, axanthone derivative, a benzoin ether, a benzoin ether derivative, analpha-ketol, an alpha-ketol derivative, and combinations thereof.

Clause 43. The acrylic polymer of any one of Clauses 1 to 42 wherein thereactive functional group is selected from the group consisting ofhydroxyl, carboxyl, carbonyl, carbonate ester, isocyanate, epoxy, vinyl,amine, amide, imide, anhydride, mercapto (thiol), acid, acrylamide,acetoacetyl groups, alkoxymethylol, cyclic ether groups, andcombinations thereof.

Clause 44. The acrylic polymer of any one of Clauses 1 to 43 wherein thereactive functional group is an acid.

Clause 45. The acrylic polymer of any one of Clauses 1 to 44 wherein theacrylic polymer has a polydispersity greater than 3.0.

Clause 46. The acrylic polymer of any one of Clauses 1 to 45 wherein theacrylic polymer has a number average molecular weight (Mn) within arange of from about 5,000 g/mol to about 150,000 g/mol.

Clause 47. The acrylic polymer of any one of Clauses 1 to 46 comprisingtwo first reactive segments A and one second segment B.

Clause 48. The acrylic polymer of Clause 47 wherein the segments A arepositioned on either side of the middle segment B on the polymer chainto define an ABA structure.

Clause 49. The acrylic polymer of any one of Clauses 1 to 46 comprisingtwo second segments B and one first reactive segment A.

Clause 50. The acrylic polymer of Clause 49 wherein the blocks B arepositioned on either side of the middle block A on the polymer chain todefine a BAB structure.

Clause 51. An acrylic polymer comprising:

-   -   at least one acrylic block copolymer including    -   a first reactive segment of controlled molecular weight and        position that includes at least one monomer having a functional        group selected from the group consisting of a UV active        functional group, a reactive functional group, a non-reactive        functional group, and combinations thereof; and    -   a second segment of controlled molecular weight and position        that includes at least one monomer having a functional group        selected from the group consisting of a reactive functional        group, a non-reactive functional group, and combinations        thereof,    -   wherein the first reactive segment includes at least one monomer        having a non-reactive functional group and at least one        polymerizable comonomer having a crosslinkable functionality,        the crosslinkable functionality selected from the group        consisting of a UV active functional group, a reactive        functional group, and combinations thereof.

Clause 52. The acrylic polymer of Clause 51 wherein the first reactivesegment includes a copolymer derived from one or more of the monomers ofthe second segment and at least one polymerizable comonomer having acrosslinkable functionality, the crosslinkable functionality selectedfrom the group consisting of a UV active functional group, a reactivefunctional group, and combinations thereof.

Clause 53. The acrylic polymer of Clauses 51 or 52 wherein the at leastone monomer having a non-reactive functional group within the firstreactive segment is the same type of monomer having a non-reactivefunctional group present in the second reactive segment.

Clause 54. The acrylic polymer of any one of Clauses 51 to 53 whereinthe acrylic polymer is a homogeneous polymer prior to crosslinking.

Clause 55. The acrylic polymer of any one of Clauses 51 to 54 whereinthe first reactive segment comprises 40% or less of the total polymermolecular weight.

Clause 56. The acrylic polymer of any one of Clauses 51 to 55 whereinthe at least one monomer having a UV active functional group is about10% or less by weight of the total polymer weight.

Clause 57. The acrylic polymer of any one of Clauses 51 to 56 whereinthe first reactive segment includes about 40% to about 99% by weight ofthe at least one monomer having a non-reactive functional group.

Clause 58. A pressure sensitive adhesive composition comprising:

-   -   the acrylic polymer of any one of Clauses 1 to 50 or Clauses 51        to 57; and    -   a crosslinking agent.

Clause 59. The adhesive composition of Clause 58 wherein thecrosslinking agent is from about 0.05% to about 5% by weight of adhesivesolids.

Clause 60. The adhesive composition of Clauses 58 or 59 wherein thecrosslinking agent is activated using one of heat, actinic radiation,electron beam radiation, and a metal based catalyst.

Clause 61. The adhesive composition of any one of Clauses 58 to 60wherein the adhesive composition further comprises at least one agentselected from the group consisting of tackifiers, plasticizers,antioxidants, pH controllers, medicaments, bactericides, growth factors,wound healing components, deodorants, perfumes, antimicrobials,fungicides, cutting agents, pigments, filler, diluents, flameretardants, and combinations thereof.

Clause 62. The adhesive composition of any one of Clauses 58 to 61wherein the weight percentage of solids is greater than 50%.

Clause 63. The adhesive composition of any one of Clauses 58 to 62wherein the adhesive exhibits an elastic/storage modulus (G′) of lessthan the Dahlquist criterion value of 3×10⁶ dynes/cm² (3×10⁵ Pa) at roomtemperature.

Clause 64. The adhesive composition of any one of Clauses 58 to 63wherein the glass transition temperature (Tg) of the adhesivecomposition is within a range of from about 15° C. to about −115° C.

Clause 65. A method of preparing a pressure sensitive adhesivecomposition comprising:

-   -   polymerizing using a controlled radical polymerization process        at least one monomer having a functional group selected from the        group consisting of a UV active functional group, a reactive        functional group, a non-reactive functional group, and        combinations thereof to thereby form a first reactive segment of        controlled molecular weight and position;    -   polymerizing using a controlled radical polymerization process        at least one monomer having a functional group selected from the        group consisting of a reactive functional group, a non-reactive        functional group, and combinations thereof to thereby form a        second segment of controlled molecular weight and position;    -   forming an acrylic polymer from the first reactive segment and        the second segment; and    -   crosslinking the acrylic polymer by mixing the acrylic polymer        with an amount of a crosslinking agent.

Clause 66. The method of Clause 65 wherein at least one of the firstreactive segment and the second segment is polymerized in the presenceof a RAFT agent.

Clause 67. The method of Clause 65 or 66 wherein at least one of thefirst reactive segment and the second segment is polymerized in thepresence of an SFRP agent.

Clause 68. An adhesive article comprising:

-   -   a substrate; and    -   the adhesive of any one of Clauses 58 to 64 disposed on the        substrate.

Clause 69. The adhesive article of Clause 68 wherein the article is inthe form of a tape.

Clause 70. An acrylic polymer consisting of:

-   -   at least one acrylic block copolymer having    -   a first reactive segment of controlled molecular weight and        position consisting of at least one monomer having a UV active        functional group, at least one monomer having a reactive        functional group, and at least one monomer having a non-reactive        functional group; and    -   a second segment of controlled molecular weight and position        consisting of at least one monomer having a reactive functional        group, and at least one monomer having a non-reactive functional        group.

Clause 71. The acrylic polymer of Clause 70 wherein the first reactivesegment consists of at least one monomer having a non-reactivefunctional group and at least one polymerizable comonomer having acrosslinkable functionality, the crosslinkable functionality consistingof a UV active functional group and a reactive functional group.

Clause 72. The acrylic polymer of Clauses 70 or 71 wherein the firstreactive segment consists of a copolymer derived from one or more of themonomers of the second segment and at least one polymerizable comonomerhaving a crosslinkable functionality, the crosslinkable functionalityconsisting of a UV active functional group and a reactive functionalgroup.

Clause 73. The acrylic polymer of any one of Clauses 70 to 72 whereinthe at least one monomer having a non-reactive functional group withinthe first reactive segment is the same type of monomer having anon-reactive functional group present in the second reactive segment.

Clause 74. The acrylic polymer of any one of Clauses 70 to 73 whereinthe acrylic polymer is a homogeneous polymer prior to crosslinking.

Clause 75. The acrylic polymer of any one of Clauses 70 to 74 whereinthe first reactive segment is about 40% or less of the total polymermolecular weight.

Clause 76. The acrylic polymer of any one of Clauses 70 to 75 whereinthe at least one monomer having a UV active functional group is about10% or less by weight of the total polymer weight.

Clause 77. The acrylic polymer of any one of Clauses 70 to 76 whereinthe first reactive segment includes about 40% to about 99% by weight ofthe at least one monomer having a non-reactive functional group.

Clause 78. A pressure sensitive adhesive composition consisting of:

-   -   the acrylic polymer of any one of Clauses 70 to 77; and    -   a crosslinking agent.

Clause 79. The adhesive composition of Clause 78 wherein thecrosslinking agent is from about 0.05% to about 5% by weight of adhesivesolids.

The features, structures, or characteristics of the invention describedthroughout this specification may be combined in any suitable manner inone or more embodiments. For example, reference throughout thisspecification to “certain embodiments,” “some embodiments,” or similarlanguage means that a particular feature, structure, or characteristicdescribed in connection with the embodiment is included in at least oneembodiment of the present invention. Thus, appearances of the phrases“in certain embodiments,” “in some embodiment,” “in other embodiments,”or similar language throughout this specification do not necessarily allrefer to the same group of embodiments and the described features,structures, or characteristics may be combined in any suitable manner inone or more embodiments.

As described hereinabove, the present subject matter solves manyproblems associated with previously known compositions and methods.However, it will be appreciated that various changes in the details,materials and arrangements of components and/or operations, which havebeen herein described and illustrated in order to explain the nature ofthe subject matter, may be made by those skilled in the art withoutdeparting from the principle and scope of the subject matter asexpressed in the appended claims.

What is claimed is:
 1. An acrylic polymer comprising: at least oneacrylic block copolymer including a first reactive segment of controlledmolecular weight and position that includes at least one monomer havinga functional group selected from the group consisting of a UV activefunctional group, a reactive functional group, a non-reactive functionalgroup, and combinations thereof; and a second segment of controlledmolecular weight and position that includes at least one monomer havinga functional group selected from the group consisting of a reactivefunctional group, a non-reactive functional group, and combinationsthereof.
 2. The acrylic polymer of claim 1 wherein the first reactivesegment includes at least one monomer having a UV active functionalgroup, at least one monomer having a reactive functional group, and atleast one monomer having a non-reactive functional group.
 3. The acrylicpolymer of claim 1 wherein the first reactive segment includes at leastone monomer having a UV active functional group and at least one monomerhaving a non-reactive functional group.
 4. The acrylic polymer of claim1 wherein the second segment includes at least one monomer having areactive functional group and at least one monomer having a non-reactivefunctional group.
 5. The acrylic polymer of claim 1 wherein the secondsegment includes at least one monomer having a non-reactive functionalgroup.
 6. The acrylic polymer of claim 1 wherein the first reactivesegment includes at least one monomer having a non-reactive functionalgroup and at least one polymerizable comonomer having a crosslinkablefunctionality, the crosslinkable functionality selected from the groupconsisting of a UV active functional group, a reactive functional group,and combinations thereof.
 7. The acrylic polymer of claim 1 wherein thefirst reactive segment includes at least one monomer having anon-reactive functional group and at least one polymerizable comonomerhaving a crosslinkable functionality, the crosslinkable functionality isa UV active functional group.
 8. The acrylic polymer of claim 1 whereinthe at least one monomer having a non-reactive functional group withinthe first reactive segment is the same type of monomer having anon-reactive functional group present in the second reactive segment. 9.The acrylic polymer of claim 1 wherein the at least one monomer having areactive functional group within the first reactive segment is the sametype of monomer having a reactive functional group present in the secondreactive segment.
 10. The acrylic polymer of claim 1 wherein the atleast one monomer having a reactive functional group includes at leastone monomer derived from the formula (II):

where R is H or CH₃ and X includes a functional group capable ofcrosslinking, wherein the functional group includes at least onefunctional group selected from the group consisting of hydroxyl,carboxyl, carbonyl, carbonate ester, isocyanate, epoxy, vinyl, amine,amide, imide, anhydride, mercapto (thiol), acid, acrylamide, acetoacetylgroups, alkoxymethylol, cyclic ether groups, and combinations thereof.11. The acrylic polymer of claim 1 wherein the at least one monomerhaving a reactive functional group includes at least one functionalizedmonomer derived from the formula (I):

where R₃ is H or CH₃ and R₄ is a branched or unbranched, saturated alkylgroup having 4 to 14 carbon atoms.
 12. The acrylic polymer of claim 1wherein the at least one functionalized monomer includes a crosslinkablefunctional group selected from the group consisting of hydroxyl,carboxyl, carbonyl, carbonate ester, isocyanate, epoxy, vinyl, amine,amide, imide, anhydride, mercapto (thiol), acid, acrylamide, acetoacetylgroups, alkoxymethylol, cyclic ether groups, and combinations thereof.13. The acrylic polymer of claim 1 wherein the at least one monomerhaving a non-reactive functional group includes at least one monomerderived from the formula (I):

where R₃ is H or CH₃ and R₄ is a branched or unbranched, saturated alkylgroup having 4 to 14 carbon atoms.
 14. The acrylic polymer of claim 1wherein the at least one monomer having a non-reactive functional groupis derived from C₁ to about C₂₀ alkyl, aryl, or cyclic acrylates or C₁to about C₂₀ alkyl, aryl, or cyclic methacrylates.
 15. The acrylicpolymer of claim 1 wherein the first reactive segment includes about 40%to about 99% by weight of the at least one monomer having a non-reactivefunctional group.
 16. The acrylic polymer of claim 1 wherein the atleast one monomer having a UV active functional group is about 10% orless by weight of the total polymer weight.
 17. The acrylic polymer ofclaim 1 wherein the second segment is non-reactive with the UV activefunctional group and/or the reactive functional group.
 18. The acrylicpolymer of claim 1 wherein the at least one monomer having anon-reactive functional group is non-reactive with the UV activefunctional group and/or the reactive functional group.
 19. The acrylicpolymer of claim 1 wherein the first reactive segment and the secondsegment are positioned adjacent to the polymer chain ends.
 20. Theacrylic polymer of claim 1 wherein the reactive functional groups and/orthe non-reactive functional groups are randomly spaced apart along thelength of the polymer chain.
 21. The acrylic polymer of claim 1 whereinthe first reactive segment comprises 40% or less of the total polymermolecular weight.
 22. The acrylic polymer of claim 1 wherein the firstreactive segment and the second segment are molecularly miscible beforecure.
 23. The acrylic polymer of claim 1 wherein the acrylic polymer isa single phase polymer at room temperature.
 24. The acrylic polymer ofclaim 1 wherein the acrylic polymer is a single phase polymer prior tocrosslinking.
 25. The acrylic polymer of claim 1 wherein the firstreactive segment and the second segment are molecularly miscible beforecure as expressed by their properties in the bulk state that areindicative of a single phase polymer.
 26. The acrylic polymer of claim 1wherein the acrylic polymer is a single phase liquid polymer at roomtemperature.
 27. The acrylic polymer of claim 1 wherein the acrylicpolymer is a single phase liquid polymer prior to crosslinking.
 28. Theacrylic polymer of claim 1 wherein the acrylic polymer is a liquidpolymer at room temperature.
 29. The acrylic polymer of claim 1 whereinthe acrylic polymer is a liquid polymer prior to crosslinking.
 30. Theacrylic polymer of claim 1 wherein the acrylic polymer is a homogeneouspolymer at room temperature.
 31. The acrylic polymer of claim 1 whereinthe acrylic polymer is a homogeneous polymer prior to crosslinking. 32.The acrylic polymer of claim 1 wherein the acrylic polymer is ahomogeneous liquid polymer prior to crosslinking.
 33. The acrylicpolymer of claim 1 wherein the acrylic polymer is a homogeneous liquidpolymer at room temperature.
 34. The acrylic polymer of claim 1 whereinthe acrylic polymer exhibits no heterogeneity prior to crosslinking. 35.The acrylic polymer of claim 1 wherein the acrylic polymer exhibits noheterogeneity at room temperature.
 36. The acrylic polymer of claim 1wherein the glass transition temperature (Tg) of the acrylic polymer iswithin a range of from about 15° C. to about −115° C.
 37. The acrylicpolymer of claim 1 wherein the UV active functional group is selectedfrom the group consisting of benzophenones, double bonds, andcombinations thereof.
 38. The acrylic polymer of claim 1 wherein the UVactive functional group is a benzophenone.
 39. The acrylic polymer ofclaim 1 wherein the UV active functional group is represented by Formula(III) as follows:

in which R₁ and R₂ is each independently an organic radical selectedfrom the group consisting of methyl, aryl, and alkyl.
 40. The acrylicpolymer of claim 1 wherein R₁ and R₂ is each independently an aromaticor substituted aromatic group.
 41. The acrylic polymer of claim 1wherein R₁ and R₂ is each independently a phenyl or substituted phenylgroup.
 42. The acrylic polymer of claim 1 wherein the UV activefunctional group is selected from the group consisting of acetophenone,an acetophenone derivative, benzophenone, a benzophenone derivative,anthraquinone, an anthraquinone derivative, benzile, a benzilederivative, thioxanthone, a thioxanthone derivative, xanthone, axanthone derivative, a benzoin ether, a benzoin ether derivative, analpha-ketol, an alpha-ketol derivative, and combinations thereof. 43.The acrylic polymer of claim 1 wherein the reactive functional group isselected from the group consisting of hydroxyl, carboxyl, carbonyl,carbonate ester, isocyanate, epoxy, vinyl, amine, amide, imide,anhydride, mercapto (thiol), acid, acrylamide, acetoacetyl groups,alkoxymethylol, cyclic ether groups, and combinations thereof.
 44. Theacrylic polymer of claim 1 wherein the reactive functional group is anacid.
 45. The acrylic polymer of claim 1 wherein the acrylic polymer hasa polydispersity greater than 3.0.
 46. The acrylic polymer of claim 1wherein the acrylic polymer has a number average molecular weight (Mn)within a range of from about 5,000 g/mol to about 150,000 g/mol.
 47. Theacrylic polymer of claim 1 comprising two first reactive segments A andone second segment B.
 48. The acrylic polymer of claim 1 claim 47wherein the segments A are positioned on either side of the middlesegment B on the polymer chain to define an ABA structure.
 49. Theacrylic polymer of claim 1 comprising two second segments B and onefirst reactive segment A.
 50. The acrylic polymer of claim 49 whereinthe blocks B are positioned on either side of the middle block A on thepolymer chain to define a BAB structure.
 51. An acrylic polymercomprising: at least one acrylic block copolymer including a firstreactive segment of controlled molecular weight and position thatincludes at least one monomer having a functional group selected fromthe group consisting of a UV active functional group, a reactivefunctional group, a non-reactive functional group, and combinationsthereof; and a second segment of controlled molecular weight andposition that includes at least one monomer having a functional groupselected from the group consisting of a reactive functional group, anon-reactive functional group, and combinations thereof, wherein thefirst reactive segment includes at least one monomer having anon-reactive functional group and at least one polymerizable comonomerhaving a crosslinkable functionality, the crosslinkable functionalityselected from the group consisting of a UV active functional group, areactive functional group, and combinations thereof.
 52. The acrylicpolymer of claim 51 wherein the first reactive segment includes acopolymer derived from one or more of the monomers of the second segmentand at least one polymerizable comonomer having a crosslinkablefunctionality, the crosslinkable functionality selected from the groupconsisting of a UV active functional group, a reactive functional group,and combinations thereof.
 53. The acrylic polymer of claim 51 whereinthe at least one monomer having a non-reactive functional group withinthe first reactive segment is the same type of monomer having anon-reactive functional group present in the second reactive segment.54. The acrylic polymer of claim 51 wherein the acrylic polymer is ahomogeneous polymer prior to crosslinking.
 55. The acrylic polymer ofclaim 51 wherein the first reactive segment comprises 40% or less of thetotal polymer molecular weight.
 56. The acrylic polymer of claim 51wherein the at least one monomer having a UV active functional group isabout 10% or less by weight of the total polymer weight.
 57. The acrylicpolymer of claim 51 wherein the first reactive segment includes about40% to about 99% by weight of the at least one monomer having anon-reactive functional group.
 58. A pressure sensitive adhesivecomposition comprising: the acrylic polymer of claim 1; and acrosslinking agent.
 59. The adhesive composition of claim 58 wherein thecrosslinking agent is from about 0.05% to about 5% by weight of adhesivesolids.
 60. The adhesive composition of claim 58 wherein thecrosslinking agent is activated using one of heat, actinic radiation,electron beam radiation, and a metal based catalyst.
 61. The adhesivecomposition of claim 58 wherein the adhesive composition furthercomprises at least one agent selected from the group consisting oftackifiers, plasticizers, antioxidants, pH controllers, medicaments,bactericides, growth factors, wound healing components, deodorants,perfumes, antimicrobials, fungicides, cutting agents, pigments, filler,diluents, flame retardants, and combinations thereof.
 62. The adhesivecomposition of claim 58 wherein the weight percentage of solids isgreater than 50%.
 63. The adhesive composition of claim 58 wherein theadhesive exhibits an elastic/storage modulus (G′) of less than theDahlquist criterion value of 3×10⁶ dynes/cm² (3×10⁵ Pa) at roomtemperature.
 64. The adhesive composition of claim 58 wherein the glasstransition temperature (Tg) of the adhesive composition is within arange of from about 15° C. to about −115° C.
 65. A method of preparing apressure sensitive adhesive composition comprising: polymerizing using acontrolled radical polymerization process at least one monomer having afunctional group selected from the group consisting of a UV activefunctional group, a reactive functional group, a non-reactive functionalgroup, and combinations thereof to thereby form a first reactive segmentof controlled molecular weight and position; polymerizing using acontrolled radical polymerization process at least one monomer having afunctional group selected from the group consisting of a reactivefunctional group, a non-reactive functional group, and combinationsthereof to thereby form a second segment of controlled molecular weightand position; forming an acrylic polymer from the first reactive segmentand the second segment; and crosslinking the acrylic polymer by mixingthe acrylic polymer with an amount of a crosslinking agent.
 66. Themethod of claim 65 wherein at least one of the first reactive segmentand the second segment is polymerized in the presence of a RAFT agent.67. The method of claim 65 wherein at least one of the first reactivesegment and the second segment is polymerized in the presence of an SFRPagent.
 68. An adhesive article comprising: a substrate; and the adhesiveof claim 58 disposed on the substrate.
 69. The adhesive article of claim68 wherein the article is in the form of a tape.
 70. An acrylic polymerconsisting of: at least one acrylic block copolymer having a firstreactive segment of controlled molecular weight and position consistingof at least one monomer having a UV active functional group, at leastone monomer having a reactive functional group, and at least one monomerhaving a non-reactive functional group; and a second segment ofcontrolled molecular weight and position consisting of at least onemonomer having a reactive functional group, and at least one monomerhaving a non-reactive functional group.
 71. The acrylic polymer of claim70 wherein the first reactive segment consists of at least one monomerhaving a non-reactive functional group and at least one polymerizablecomonomer having a crosslinkable functionality, the crosslinkablefunctionality consisting of a UV active functional group and a reactivefunctional group.
 72. The acrylic polymer of claim 70 wherein the firstreactive segment consists of a copolymer derived from one or more of themonomers of the second segment and at least one polymerizable comonomerhaving a crosslinkable functionality, the crosslinkable functionalityconsisting of a UV active functional group and a reactive functionalgroup.
 73. The acrylic polymer of claim 70 wherein the at least onemonomer having a non-reactive functional group within the first reactivesegment is the same type of monomer having a non-reactive functionalgroup present in the second reactive segment.
 74. The acrylic polymer ofclaim 70 wherein the acrylic polymer is a homogeneous polymer prior tocrosslinking.
 75. The acrylic polymer of claim 70 wherein the firstreactive segment is about 40% or less of the total polymer molecularweight.
 76. The acrylic polymer of claim 70 wherein the at least onemonomer having a UV active functional group is about 10% or less byweight of the total polymer weight.
 77. The acrylic polymer of claim 70wherein the first reactive segment includes about 40% to about 99% byweight of the at least one monomer having a non-reactive functionalgroup.
 78. A pressure sensitive adhesive composition consisting of: theacrylic polymer of claim 70; and a crosslinking agent.
 79. The adhesivecomposition of claim 78 wherein the crosslinking agent is from about0.05% to about 5% by weight of adhesive solids.